Merge pull request #442 from edx/felix/formula-hints

Crowdsourced Hints - "0.2 release"

common/lib/capa/capa/responsetypes.py

@@ -915,7 +915,26 @@ class NumericalResponse(LoncapaResponse):
         else:
             return CorrectMap(self.answer_id, 'incorrect')
 
-    # TODO: add check_hint_condition(self, hxml_set, student_answers)
+    def compare_answer(self, ans1, ans2):
+        """
+        Outside-facing function that lets us compare two numerical answers,
+        with this problem's tolerance.
+        """
+        return compare_with_tolerance(
+            evaluator({}, {}, ans1),
+            evaluator({}, {}, ans2),
+            self.tolerance
+        )
+
+    def validate_answer(self, answer):
+        """
+        Returns whether this answer is in a valid form.
+        """
+        try:
+            evaluator(dict(), dict(), answer)
+            return True
+        except (StudentInputError, UndefinedVariable):
+            return False
 
     def get_answers(self):
         return {self.answer_id: self.correct_answer}
@@ -1778,46 +1797,24 @@ class FormulaResponse(LoncapaResponse):
             self.correct_answer, given, self.samples)
         return CorrectMap(self.answer_id, correctness)
 
-    def check_formula(self, expected, given, samples):
-        variables = samples.split('@')[0].split(',')
-        numsamples = int(samples.split('@')[1].split('#')[1])
-        sranges = zip(*map(lambda x: map(float, x.split(",")),
-                           samples.split('@')[1].split('#')[0].split(':')))
-
-        ranges = dict(zip(variables, sranges))
-        for _ in range(numsamples):
-            instructor_variables = self.strip_dict(dict(self.context))
-            student_variables = {}
-            # ranges give numerical ranges for testing
-            for var in ranges:
-                # TODO: allow specified ranges (i.e. integers and complex numbers) for random variables
-                value = random.uniform(*ranges[var])
-                instructor_variables[str(var)] = value
-                student_variables[str(var)] = value
-            # log.debug('formula: instructor_vars=%s, expected=%s' %
-            # (instructor_variables,expected))
-
-            # Call `evaluator` on the instructor's answer and get a number
-            instructor_result = evaluator(
-                instructor_variables, {},
-                expected, case_sensitive=self.case_sensitive
-            )
+    def tupleize_answers(self, answer, var_dict_list):
+        """
+        Takes in an answer and a list of dictionaries mapping variables to values.
+        Each dictionary represents a test case for the answer.
+        Returns a tuple of formula evaluation results.
+        """
+        out = []
+        for var_dict in var_dict_list:
             try:
-                # log.debug('formula: student_vars=%s, given=%s' %
-                # (student_variables,given))
-
-                # Call `evaluator` on the student's answer; look for exceptions
-                student_result = evaluator(
-                    student_variables,
-                    {},
-                    given,
-                    case_sensitive=self.case_sensitive
-                )
+                out.append(evaluator(
+                    var_dict,
+                    dict(),
+                    answer,
+                    case_sensitive=self.case_sensitive,
+                ))
             except UndefinedVariable as uv:
                 log.debug(
-                    'formularesponse: undefined variable in given=%s',
-                    given
-                )
+                    'formularesponse: undefined variable in formula=%s' % answer)
                 raise StudentInputError(
                     "Invalid input: " + uv.message + " not permitted in answer"
                 )
@@ -1840,17 +1837,70 @@ class FormulaResponse(LoncapaResponse):
                 # If non-factorial related ValueError thrown, handle it the same as any other Exception
                 log.debug('formularesponse: error {0} in formula'.format(ve))
                 raise StudentInputError("Invalid input: Could not parse '%s' as a formula" %
-                                        cgi.escape(given))
+                                        cgi.escape(answer))
             except Exception as err:
                 # traceback.print_exc()
                 log.debug('formularesponse: error %s in formula', err)
                 raise StudentInputError("Invalid input: Could not parse '%s' as a formula" %
-                                        cgi.escape(given))
+                                        cgi.escape(answer))
+        return out
 
-            # No errors in student's response--actually test for correctness
-            if not compare_with_tolerance(student_result, instructor_result, self.tolerance):
-                return "incorrect"
-        return "correct"
+    def randomize_variables(self, samples):
+        """
+        Returns a list of dictionaries mapping variables to random values in range,
+        as expected by tupleize_answers.
+        """
+        variables = samples.split('@')[0].split(',')
+        numsamples = int(samples.split('@')[1].split('#')[1])
+        sranges = zip(*map(lambda x: map(float, x.split(",")),
+                           samples.split('@')[1].split('#')[0].split(':')))
+        ranges = dict(zip(variables, sranges))
+
+        out = []
+        for i in range(numsamples):
+            var_dict = {}
+            # ranges give numerical ranges for testing
+            for var in ranges:
+                # TODO: allow specified ranges (i.e. integers and complex numbers) for random variables
+                value = random.uniform(*ranges[var])
+                var_dict[str(var)] = value
+            out.append(var_dict)
+        return out
+
+    def check_formula(self, expected, given, samples):
+        """
+        Given an expected answer string, a given (student-produced) answer
+        string, and a samples string, return whether the given answer is
+        "correct" or "incorrect".
+        """
+        var_dict_list = self.randomize_variables(samples)
+        student_result = self.tupleize_answers(given, var_dict_list)
+        instructor_result = self.tupleize_answers(expected, var_dict_list)
+
+        correct = all(compare_with_tolerance(student, instructor, self.tolerance)
+                      for student, instructor in zip(student_result, instructor_result))
+        if correct:
+            return "correct"
+        else:
+            return "incorrect"
+
+    def compare_answer(self, ans1, ans2):
+        """
+        An external interface for comparing whether a and b are equal.
+        """
+        internal_result = self.check_formula(ans1, ans2, self.samples)
+        return internal_result == "correct"
+
+    def validate_answer(self, answer):
+        """
+        Returns whether this answer is in a valid form.
+        """
+        var_dict_list = self.randomize_variables(self.samples)
+        try:
+            self.tupleize_answers(answer, var_dict_list)
+            return True
+        except StudentInputError:
+            return False
 
     def strip_dict(self, d):
         ''' Takes a dict. Returns an identical dict, with all non-word

common/lib/capa/capa/tests/test_responsetypes.py

@@ -496,6 +496,20 @@ class FormulaResponseTest(ResponseTest):
         input_dict = {'1_2_1': '1/0'}
         self.assertRaises(StudentInputError, problem.grade_answers, input_dict)
 
+    def test_validate_answer(self):
+        """
+        Makes sure that validate_answer works.
+        """
+        sample_dict = {'x': (1, 2)}
+        problem = self.build_problem(
+            sample_dict=sample_dict,
+            num_samples=10,
+            tolerance="1%",
+            answer="x"
+        )
+        self.assertTrue(problem.responders.values()[0].validate_answer('14*x'))
+        self.assertFalse(problem.responders.values()[0].validate_answer('3*y+2*x'))
+
 
 class StringResponseTest(ResponseTest):
     from capa.tests.response_xml_factory import StringResponseXMLFactory
@@ -915,6 +929,20 @@ class NumericalResponseTest(ResponseTest):
                 with self.assertRaisesRegexp(StudentInputError, msg_regex):
                     problem.grade_answers({'1_2_1': 'foobar'})
 
+    def test_compare_answer(self):
+        """Tests the answer compare function."""
+        problem = self.build_problem(answer="42")
+        responder = problem.responders.values()[0]
+        self.assertTrue(responder.compare_answer('48', '8*6'))
+        self.assertFalse(responder.compare_answer('48', '9*5'))
+
+    def test_validate_answer(self):
+        """Tests the answer validation function."""
+        problem = self.build_problem(answer="42")
+        responder = problem.responders.values()[0]
+        self.assertTrue(responder.validate_answer('23.5'))
+        self.assertFalse(responder.validate_answer('fish'))
+
 
 class CustomResponseTest(ResponseTest):
     from capa.tests.response_xml_factory import CustomResponseXMLFactory

common/lib/xmodule/xmodule/crowdsource_hinter.py

@@ -7,15 +7,18 @@ Currently experimental - not for instructor use, yet.
 import logging
 import json
 import random
+import copy
 
 from pkg_resources import resource_string
 
 from lxml import etree
 
 from xmodule.x_module import XModule
-from xmodule.xml_module import XmlDescriptor
+from xmodule.raw_module import RawDescriptor
 from xblock.core import Scope, String, Integer, Boolean, Dict, List
 
+from capa.responsetypes import FormulaResponse
+
 from django.utils.html import escape
 
 log = logging.getLogger(__name__)
@@ -37,10 +40,15 @@ class CrowdsourceHinterFields(object):
     mod_queue = Dict(help='A dictionary containing hints still awaiting approval', scope=Scope.content,
                      default={})
     hint_pk = Integer(help='Used to index hints.', scope=Scope.content, default=0)
-    # A list of previous answers this student made to this problem.
-    # Of the form [answer, [hint_pk_1, hint_pk_2, hint_pk_3]] for each problem.  hint_pk's are
-    # None if the hint was not given.
-    previous_answers = List(help='A list of previous submissions.', scope=Scope.user_state, default=[])
+
+    # A list of previous hints that a student viewed.
+    # Of the form [answer, [hint_pk_1, ...]] for each problem.
+    # Sorry about the variable name - I know it's confusing.
+    previous_answers = List(help='A list of hints viewed.', scope=Scope.user_state, default=[])
+
+    # user_submissions actually contains a list of previous answers submitted.
+    # (Originally, preivous_answers did this job, hence the name confusion.)
+    user_submissions = List(help='A list of previous submissions', scope=Scope.user_state, default=[])
     user_voted = Boolean(help='Specifies if the user has voted on this problem or not.',
                          scope=Scope.user_state, default=False)
 
@@ -68,6 +76,26 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
 
     def __init__(self, *args, **kwargs):
         XModule.__init__(self, *args, **kwargs)
+        # We need to know whether we are working with a FormulaResponse problem.
+        try:
+            responder = self.get_display_items()[0].lcp.responders.values()[0]
+        except (IndexError, AttributeError):
+            log.exception('Unable to find a capa problem child.')
+            return
+
+        self.is_formula = isinstance(self, FormulaResponse)
+        if self.is_formula:
+            self.answer_to_str = self.formula_answer_to_str
+        else:
+            self.answer_to_str = self.numerical_answer_to_str
+        # compare_answer is expected to return whether its two inputs are close enough
+        # to be equal, or raise a StudentInputError if one of the inputs is malformatted.
+        if hasattr(responder, 'compare_answer') and hasattr(responder, 'validate_answer'):
+            self.compare_answer = responder.compare_answer
+            self.validate_answer = responder.validate_answer
+        else:
+            # This response type is not supported!
+            log.exception('Response type not supported for hinting: ' + str(responder))
 
     def get_html(self):
         """
@@ -98,14 +126,29 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
 
         return out
 
-    def capa_answer_to_str(self, answer):
+    def numerical_answer_to_str(self, answer):
         """
-        Converts capa answer format to a string representation
+        Converts capa numerical answer format to a string representation
         of the answer.
         -Lon-capa dependent.
         -Assumes that the problem only has one part.
         """
-        return str(float(answer.values()[0]))
+        return str(answer.values()[0])
+
+    def formula_answer_to_str(self, answer):
+        """
+        Converts capa formula answer into a string.
+        -Lon-capa dependent.
+        -Assumes that the problem only has one part.
+        """
+        return str(answer.values()[0])
+
+    def get_matching_answers(self, answer):
+        """
+        Look in self.hints, and find all answer keys that are "equal with tolerance"
+        to the input answer.
+        """
+        return [key for key in self.hints if self.compare_answer(key, answer)]
 
     def handle_ajax(self, dispatch, data):
         """
@@ -124,6 +167,9 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
 
         if out is None:
             out = {'op': 'empty'}
+        elif 'error' in out:
+            # Error in processing.
+            out.update({'op': 'error'})
         else:
             out.update({'op': dispatch})
         return json.dumps({'contents': self.system.render_template('hinter_display.html', out)})
@@ -134,51 +180,67 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
 
         Called by hinter javascript after a problem is graded as incorrect.
         Args:
-        `data` -- must be interpretable by capa_answer_to_str.
+        `data` -- must be interpretable by answer_to_str.
         Output keys:
-            - 'best_hint' is the hint text with the most votes.
-            - 'rand_hint_1' and 'rand_hint_2' are two random hints to the answer in `data`.
+            - 'hints' is a list of hint strings to show to the user.
             - 'answer' is the parsed answer that was submitted.
+        Will record the user's wrong answer in user_submissions, and the hints shown
+        in previous_answers.
         """
+        # First, validate our inputs.
         try:
-            answer = self.capa_answer_to_str(data)
-        except ValueError:
+            answer = self.answer_to_str(data)
+        except (ValueError, AttributeError):
             # Sometimes, we get an answer that's just not parsable.  Do nothing.
             log.exception('Answer not parsable: ' + str(data))
             return
-        # Look for a hint to give.
-        # Make a local copy of self.hints - this means we only need to do one json unpacking.
-        # (This is because xblocks storage makes the following command a deep copy.)
-        local_hints = self.hints
-        if (answer not in local_hints) or (len(local_hints[answer]) == 0):
+        if not self.validate_answer(answer):
+            # Answer is not in the right form.
+            log.exception('Answer not valid: ' + str(answer))
+            return
+        if answer not in self.user_submissions:
+            self.user_submissions += [answer]
+
+        # For all answers similar enough to our own, accumulate all hints together.
+        # Also track the original answer of each hint.
+        matching_answers = self.get_matching_answers(answer)
+        matching_hints = {}
+        for matching_answer in matching_answers:
+            temp_dict = copy.deepcopy(self.hints[matching_answer])
+            for key, value in temp_dict.items():
+                # Each value now has hint, votes, matching_answer.
+                temp_dict[key] = value + [matching_answer]
+            matching_hints.update(temp_dict)
+        # matching_hints now maps pk's to lists of [hint, votes, matching_answer]
+
+        # Finally, randomly choose a subset of matching_hints to actually show.
+        if not matching_hints:
             # No hints to give.  Return.
-            self.previous_answers += [[answer, [None, None, None]]]
             return
         # Get the top hint, plus two random hints.
-        n_hints = len(local_hints[answer])
-        best_hint_index = max(local_hints[answer], key=lambda key: local_hints[answer][key][1])
-        best_hint = local_hints[answer][best_hint_index][0]
-        if len(local_hints[answer]) == 1:
-            rand_hint_1 = ''
-            rand_hint_2 = ''
-            self.previous_answers += [[answer, [best_hint_index, None, None]]]
-        elif n_hints == 2:
-            best_hint = local_hints[answer].values()[0][0]
-            best_hint_index = local_hints[answer].keys()[0]
-            rand_hint_1 = local_hints[answer].values()[1][0]
-            hint_index_1 = local_hints[answer].keys()[1]
-            rand_hint_2 = ''
-            self.previous_answers += [[answer, [best_hint_index, hint_index_1, None]]]
-        else:
-            (hint_index_1, rand_hint_1), (hint_index_2, rand_hint_2) =\
-                random.sample(local_hints[answer].items(), 2)
-            rand_hint_1 = rand_hint_1[0]
-            rand_hint_2 = rand_hint_2[0]
-            self.previous_answers += [[answer, [best_hint_index, hint_index_1, hint_index_2]]]
-
-        return {'best_hint': best_hint,
-                'rand_hint_1': rand_hint_1,
-                'rand_hint_2': rand_hint_2,
+        n_hints = len(matching_hints)
+        hints = []
+        # max(dict) returns the maximum key in dict.
+        # The key function takes each pk, and returns the number of votes for the
+        # hint with that pk.
+        best_hint_index = max(matching_hints, key=lambda pk: matching_hints[pk][1])
+        hints.append(matching_hints[best_hint_index][0])
+        best_hint_answer = matching_hints[best_hint_index][2]
+        # The brackets surrounding the index are for backwards compatability purposes.
+        # (It used to be that each answer was paired with multiple hints in a list.)
+        self.previous_answers += [[best_hint_answer, [best_hint_index]]]
+        for _ in xrange(min(2, n_hints - 1)):
+            # Keep making random hints until we hit a target, or run out.
+            while True:
+                # random.choice randomly chooses an element from its input list.
+                # (We then unpack the item, in this case data for a hint.)
+                (hint_index, (rand_hint, _, hint_answer)) =\
+                    random.choice(matching_hints.items())
+                if rand_hint not in hints:
+                    break
+            hints.append(rand_hint)
+            self.previous_answers += [[hint_answer, [hint_index]]]
+        return {'hints': hints,
                 'answer': answer}
 
     def get_feedback(self, data):
@@ -188,38 +250,37 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
         Args:
         `data` -- not actually used.  (It is assumed that the answer is correct.)
         Output keys:
-            - 'index_to_hints' maps previous answer indices to hints that the user saw earlier.
-            - 'index_to_answer' maps previous answer indices to the actual answer submitted.
+            - 'answer_to_hints': a nested dictionary.
+              answer_to_hints[answer][hint_pk] returns the text of the hint.
+            - 'user_submissions': the same thing as self.user_submissions.  A list of
+              the answers that the user previously submitted.
         """
         # The student got it right.
         # Did he submit at least one wrong answer?
-        if len(self.previous_answers) == 0:
+        if len(self.user_submissions) == 0:
             # No.  Nothing to do here.
             return
         # Make a hint-voting interface for each wrong answer.  The student will only
         # be allowed to make one vote / submission, but he can choose which wrong answer
         # he wants to look at.
-        # index_to_hints[previous answer #] = [(hint text, hint pk), + ]
-        index_to_hints = {}
-        # index_to_answer[previous answer #] = answer text
-        index_to_answer = {}
+        answer_to_hints = {}    # answer_to_hints[answer text][hint pk] -> hint text
 
         # Go through each previous answer, and populate index_to_hints and index_to_answer.
         for i in xrange(len(self.previous_answers)):
             answer, hints_offered = self.previous_answers[i]
-            index_to_hints[i] = []
-            index_to_answer[i] = answer
+            if answer not in answer_to_hints:
+                answer_to_hints[answer] = {}
             if answer in self.hints:
                 # Go through each hint, and add to index_to_hints
                 for hint_id in hints_offered:
-                    if hint_id is not None:
+                    if (hint_id is not None) and (hint_id not in answer_to_hints[answer]):
                         try:
-                            index_to_hints[i].append((self.hints[answer][str(hint_id)][0], hint_id))
+                            answer_to_hints[answer][hint_id] = self.hints[answer][str(hint_id)][0]
                         except KeyError:
                             # Sometimes, the hint that a user saw will have been deleted by the instructor.
                             continue
-
-        return {'index_to_hints': index_to_hints, 'index_to_answer': index_to_answer}
+        return {'answer_to_hints': answer_to_hints,
+                'user_submissions': self.user_submissions}
 
     def tally_vote(self, data):
         """
@@ -227,31 +288,51 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
 
         Args:
         `data` -- expected to have the following keys:
-            'answer': ans_no (index in previous_answers)
+            'answer': text of answer we're voting on
             'hint': hint_pk
+            'pk_list': A list of [answer, pk] pairs, each of which representing a hint.
+                       We will return a list of how many votes each hint in the list has so far.
+                       It's up to the browser to specify which hints to return vote counts for.
+
         Returns key 'hint_and_votes', a list of (hint_text, #votes) pairs.
         """
         if self.user_voted:
-            return {}
-        ans_no = int(data['answer'])
-        hint_no = str(data['hint'])
-        answer = self.previous_answers[ans_no][0]
+            return {'error': 'Sorry, but you have already voted!'}
+        ans = data['answer']
+        if not self.validate_answer(ans):
+            # Uh oh.  Invalid answer.
+            log.exception('Failure in hinter tally_vote: Unable to parse answer: {ans}'.format(ans=ans))
+            return {'error': 'Failure in voting!'}
+        hint_pk = str(data['hint'])
         # We use temp_dict because we need to do a direct write for the database to update.
         temp_dict = self.hints
-        temp_dict[answer][hint_no][1] += 1
+        try:
+            temp_dict[ans][hint_pk][1] += 1
+        except KeyError:
+            log.exception('''Failure in hinter tally_vote: User voted for non-existant hint:
+                             Answer={ans} pk={hint_pk}'''.format(ans=ans, hint_pk=hint_pk))
+            return {'error': 'Failure in voting!'}
         self.hints = temp_dict
         # Don't let the user vote again!
         self.user_voted = True
 
         # Return a list of how many votes each hint got.
+        pk_list = json.loads(data['pk_list'])
         hint_and_votes = []
-        for hint_no in self.previous_answers[ans_no][1]:
-            if hint_no is None:
+        for answer, vote_pk in pk_list:
+            if not self.validate_answer(answer):
+                log.exception('In hinter tally_vote, couldn\'t parse {ans}'.format(ans=answer))
                 continue
-            hint_and_votes.append(temp_dict[answer][str(hint_no)])
+            try:
+                hint_and_votes.append(temp_dict[answer][str(vote_pk)])
+            except KeyError:
+                log.exception('In hinter tally_vote, couldn\'t find: {ans}, {vote_pk}'.format(
+                              ans=answer, vote_pk=str(vote_pk)))
 
-        # Reset self.previous_answers.
+        hint_and_votes.sort(key=lambda pair: pair[1], reverse=True)
+        # Reset self.previous_answers and user_submissions.
         self.previous_answers = []
+        self.user_submissions = []
         return {'hint_and_votes': hint_and_votes}
 
     def submit_hint(self, data):
@@ -260,13 +341,17 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
 
         Args:
         `data` -- expected to have the following keys:
-            'answer': answer index in previous_answers
+            'answer': text of answer
             'hint': text of the new hint that the user is adding
         Returns a thank-you message.
         """
         # Do html escaping.  Perhaps in the future do profanity filtering, etc. as well.
         hint = escape(data['hint'])
-        answer = self.previous_answers[int(data['answer'])][0]
+        answer = data['answer']
+        if not self.validate_answer(answer):
+            log.exception('Failure in hinter submit_hint: Unable to parse answer: {ans}'.format(
+                          ans=answer))
+            return {'error': 'Could not submit answer'}
         # Only allow a student to vote or submit a hint once.
         if self.user_voted:
             return {'message': 'Sorry, but you have already voted!'}
@@ -277,9 +362,9 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
         else:
             temp_dict = self.hints
         if answer in temp_dict:
-            temp_dict[answer][self.hint_pk] = [hint, 1]     # With one vote (the user himself).
+            temp_dict[answer][str(self.hint_pk)] = [hint, 1]     # With one vote (the user himself).
         else:
-            temp_dict[answer] = {self.hint_pk: [hint, 1]}
+            temp_dict[answer] = {str(self.hint_pk): [hint, 1]}
         self.hint_pk += 1
         if self.moderate == 'True':
             self.mod_queue = temp_dict
@@ -288,10 +373,11 @@ class CrowdsourceHinterModule(CrowdsourceHinterFields, XModule):
         # Mark the user has having voted; reset previous_answers
         self.user_voted = True
         self.previous_answers = []
+        self.user_submissions = []
         return {'message': 'Thank you for your hint!'}
 
 
-class CrowdsourceHinterDescriptor(CrowdsourceHinterFields, XmlDescriptor):
+class CrowdsourceHinterDescriptor(CrowdsourceHinterFields, RawDescriptor):
     module_class = CrowdsourceHinterModule
     stores_state = True
 

common/lib/xmodule/xmodule/css/crowdsource_hinter/display.scss

@@ -7,52 +7,6 @@
   background: rgb(253, 248, 235);
 }
 
-#answer-tabs {
-  background: #FFFFFF;
-  border: none;
-  margin-bottom: 20px;
-  padding-bottom: 20px;
-}
-
-#answer-tabs .ui-widget-header {
-  border-bottom: 1px solid #DCDCDC;
-  background: #FDF8EB;
-}
-
-#answer-tabs .ui-tabs-nav .ui-state-default {
-  border: 1px solid #DCDCDC;
-  background: #E6E6E3;
-  margin-bottom: 0px;
-}
-
-#answer-tabs .ui-tabs-nav .ui-state-default:hover {
-  background: #FFFFFF;
-}
-
-#answer-tabs .ui-tabs-nav .ui-state-active:hover {
-  background: #FFFFFF;
-}
-
-#answer-tabs .ui-tabs-nav .ui-state-active {
-  border: 1px solid #DCDCDC;
-  background: #FFFFFF;
-}
-
-#answer-tabs .ui-tabs-nav .ui-state-active a {
-  color: #222222;
-  background: #FFFFFF;
-}
-
-#answer-tabs .ui-tabs-nav .ui-state-default a:hover {
-  color: #222222;
-  background: #FFFFFF;
-}
-
-#answer-tabs .custom-hint {
-  height: 100px;
-  width: 100%;
-}
-
 .hint-inner-container {
   padding-left: 15px;
   padding-right: 15px;
@@ -63,3 +17,24 @@
   padding-top: 0px !important;
   padding-bottom: 0px !important;
 }
+
+.wizard-view {
+  float: left;
+  width: 790px;
+  margin-right: 10px;
+}
+
+.wizard-container {
+  width: 3000px;
+
+  -webkit-transition:all 1.0s ease-in-out;
+  -moz-transition:all 1.0s ease-in-out;
+  -o-transition:all 1.0s ease-in-out;
+  transition:all 1.0s ease-in-out;
+}
+
+.wizard-viewbox {
+  width: 800px;
+  overflow: hidden;
+  position: relative;
+}

common/lib/xmodule/xmodule/js/fixtures/crowdsource_hinter.html

+<li id="vert-0" data-id="i4x://Me/19.002/crowdsource_hinter/crowdsource_hinter_def7a1142dd0">
+    
+
+<section class="xmodule_display xmodule_CrowdsourceHinterModule" data-type="Hinter" id="hinter-root">
+    
+
+<section class="xmodule_display xmodule_CapaModule" data-type="Problem" id="problem">
+  <section id="problem_i4x-Me-19_002-problem-Numerical_Input" class="problems-wrapper" data-problem-id="i4x://Me/19.002/problem/Numerical_Input" data-url="/courses/Me/19.002/Test/modx/i4x://Me/19.002/problem/Numerical_Input" data-progress_status="done" data-progress_detail="1/1">
+
+
+    <h2 class="problem-header">
+      Numerical Input
+    </h2>
+
+    <section class="problem-progress">(1/1 points)</section>
+
+    <section class="problem">
+      <div><p>The answer is 2*x^2*y + 5
+          </p><span><br><span> Answer =</span>
+          <section id="inputtype_i4x-Me-19_002-problem-Numerical_Input_2_1" class="text-input-dynamath capa_inputtype ">
+            <div class="correct " id="status_i4x-Me-19_002-problem-Numerical_Input_2_1">
+              <input type="text" name="input_i4x-Me-19_002-problem-Numerical_Input_2_1" id="input_i4x-Me-19_002-problem-Numerical_Input_2_1" aria-describedby="answer_i4x-Me-19_002-problem-Numerical_Input_2_1" value="2*x^2*y +5" class="math" size="40">
+
+        </div></section></span>
+
+        <input type="file" />
+
+        <section class="solution-span"><span id="solution_i4x-Me-19_002-problem-Numerical_Input_solution_1"></span></section></div>
+
+      <section class="action">
+        <input type="hidden" name="problem_id" value="Numerical Input">
+
+        <input class="check Check" type="button" value="Check">
+        <button class="show"><span class="show-label">Show Answer(s)</span> <span class="sr">(for question(s) above - adjacent to each field)</span></button>
+      </section>
+    </section>
+  </section>
+
+</section>
+
+
+
+<div id="i4x_Me_19_002_problem_Numerical_Input_setup"></div>
+
+
+
+<section class="crowdsource-wrapper" data-url="/courses/Me/19.002/Test/modx/i4x://Me/19.002/crowdsource_hinter/crowdsource_hinter_def7a1142dd0" data-child-url="/courses/Me/19.002/Test/modx/i4x://Me/19.002/problem/Numerical_Input" style="display: none;"> </section>
+</section>
+
+
+
+</li>
\ No newline at end of file

common/lib/xmodule/xmodule/js/spec/capa/display_spec.coffee

@@ -125,9 +125,10 @@ describe 'Problem', ->
         expect(@problem.bind).toHaveBeenCalled()
 
   describe 'check_fd', ->
-    xit 'should have specs written for this functionality', ->
+    xit 'should have more specs written for this functionality', ->
       expect(false)
 
+
   describe 'check', ->
     beforeEach ->
       @problem = new Problem($('.xmodule_display'))
@@ -137,6 +138,15 @@ describe 'Problem', ->
       @problem.check()
       expect(Logger.log).toHaveBeenCalledWith 'problem_check', 'foo=1&bar=2'
 
+    it 'log the problem_graded event, after the problem is done grading.', ->
+      spyOn($, 'postWithPrefix').andCallFake (url, answers, callback) ->
+        response = 
+          success: 'correct'
+          contents: 'mock grader response'
+        callback(response)
+      @problem.check()
+      expect(Logger.log).toHaveBeenCalledWith 'problem_graded', ['foo=1&bar=2', 'mock grader response'], @problem.url
+
     it 'submit the answer for check', ->
       spyOn $, 'postWithPrefix'
       @problem.check()

common/lib/xmodule/xmodule/js/spec/crowdsource_hinter/display_spec.coffee

+describe 'Crowdsourced hinter', ->  
+  beforeEach ->
+    window.update_schematics = ->
+    jasmine.stubRequests()
+    # note that the fixturesPath is set in spec/helper.coffee
+    loadFixtures 'crowdsource_hinter.html'
+    @hinter = new Hinter($('#hinter-root'))
+
+  describe 'high-level integration tests', ->
+    # High-level, happy-path tests for integration with capa problems.
+    beforeEach ->
+      # Make a more thorough $.postWithPrefix mock.
+      spyOn($, 'postWithPrefix').andCallFake( ->
+        last_argument = arguments[arguments.length - 1]
+        if typeof last_argument == 'function'
+          response = 
+            success: 'incorrect'
+            contents: 'mock grader response'
+          last_argument(response)
+      )
+      @problem = new Problem($('#problem'))
+      @problem.bind()
+
+    it 'knows when a capa problem is graded, using check.', ->
+      @problem.answers = 'test answer'
+      @problem.check()
+      expect($.postWithPrefix).toHaveBeenCalledWith("#{@hinter.url}/get_hint", 'test answer', jasmine.any(Function))
+
+    it 'knows when a capa problem is graded usig check_fd.', ->
+      spyOn($, 'ajaxWithPrefix').andCallFake((url, settings) ->
+        response = 
+          success: 'incorrect'
+          contents: 'mock grader response'
+        settings.success(response)
+      )
+      @problem.answers = 'test answer'
+      @problem.check_fd()
+      expect($.postWithPrefix).toHaveBeenCalledWith("#{@hinter.url}/get_hint", 'test answer', jasmine.any(Function))
+
+  describe 'capture_problem', ->
+    beforeEach ->
+      spyOn($, 'postWithPrefix').andReturn(null)
+
+    it 'gets hints for an incorrect answer', ->
+      data = ['some answers', '<thing class="incorrect">']
+      @hinter.capture_problem('problem_graded', data, 'fake element')
+      expect($.postWithPrefix).toHaveBeenCalledWith("#{@hinter.url}/get_hint", 'some answers', jasmine.any(Function))
+
+    it 'gets feedback for a correct answer', ->
+      data = ['some answers', '<thing class="correct">']
+      @hinter.capture_problem('problem_graded', data, 'fake element')
+      expect($.postWithPrefix).toHaveBeenCalledWith("#{@hinter.url}/get_feedback", 'some answers', jasmine.any(Function))
+
+

common/lib/xmodule/xmodule/js/src/capa/display.coffee

@@ -19,7 +19,6 @@ class @Problem
 
     problem_prefix = @element_id.replace(/problem_/,'')
     @inputs = @$("[id^=input_#{problem_prefix}_]")
-
     @$('section.action input:button').click @refreshAnswers
     @$('section.action input.check').click @check_fd
     @$('section.action input.reset').click @reset
@@ -247,6 +246,7 @@ class @Problem
             @updateProgress response
           else
             @gentle_alert response.success
+        Logger.log 'problem_graded', [@answers, response.contents], @url
 
     if not abort_submission
       $.ajaxWithPrefix("#{@url}/problem_check", settings)

common/lib/xmodule/xmodule/js/src/crowdsource_hinter/display.coffee

@@ -29,42 +29,73 @@ class @Hinter
     $(selector, @el)
 
   bind: =>
-    window.update_schematics()
     @$('input.vote').click @vote
     @$('input.submit-hint').click @submit_hint
     @$('.custom-hint').click @clear_default_text
-    @$('#answer-tabs').tabs({active: 0})
-    @$('.expand-goodhint').click @expand_goodhint
+    @$('.expand').click @expand
+    @$('.wizard-link').click @wizard_link_handle
+    @$('.answer-choice').click @answer_choice_handle
 
-  expand_goodhint: =>
-    if @$('.goodhint').css('display') == 'none'
-      @$('.goodhint').css('display', 'block')
+  expand: (eventObj) =>
+    # Expand a hidden div.
+    target = @$('#' + @$(eventObj.currentTarget).data('target'))
+    if @$(target).css('display') == 'none'
+      @$(target).css('display', 'block')
     else
-      @$('.goodhint').css('display', 'none')
+      @$(target).css('display', 'none')
+    # Fix positioning errors with the bottom class.
+    @set_bottom_links()
 
   vote: (eventObj) =>
+    # Make an ajax request with the user's vote.
     target = @$(eventObj.currentTarget)
-    post_json = {'answer': target.data('answer'), 'hint': target.data('hintno')}
+    all_pks = @$('#pk-list').attr('data-pk-list')
+    post_json = {'answer': target.attr('data-answer'), 'hint': target.data('hintno'), 'pk_list': all_pks}
     $.postWithPrefix "#{@url}/vote", post_json, (response) =>
       @render(response.contents)
 
   submit_hint: (eventObj) =>
-    target = @$(eventObj.currentTarget)
-    textarea_id = '#custom-hint-' + target.data('answer')
-    post_json = {'answer': target.data('answer'), 'hint': @$(textarea_id).val()}
+    # Make an ajax request with the user's new hint.
+    textarea = $('.custom-hint')
+    if @answer == ''
+      # The user didn't choose an answer, somehow.  Do nothing.
+      return
+    post_json = {'answer': @answer, 'hint': textarea.val()}
     $.postWithPrefix "#{@url}/submit_hint",post_json, (response) =>
       @render(response.contents)
 
   clear_default_text: (eventObj) =>
+    # Remove placeholder text in the hint submission textbox.
     target = @$(eventObj.currentTarget)
     if target.data('cleared') == undefined
       target.val('')
       target.data('cleared', true)
 
+  wizard_link_handle: (eventObj) =>
+    # Move to another wizard view, based on the link that the user clicked.
+    target = @$(eventObj.currentTarget)
+    @go_to(target.attr('dest'))
+
+  answer_choice_handle: (eventObj) =>
+    # A special case of wizard_link_handle - we need to track a state variable,
+    # the answer that the user chose.
+    @answer = @$(eventObj.target).attr('value')
+    @$('#blank-answer').html(@answer)
+    @go_to('p3')
+
+  set_bottom_links: =>
+    # Makes each .bottom class stick to the bottom of .wizard-viewbox
+    @$('.bottom').css('margin-top', '0px')
+    viewbox_height = parseInt(@$('.wizard-viewbox').css('height'), 10)
+    @$('.bottom').each((index, obj) ->
+      view_height = parseInt($(obj).parent().css('height'), 10)
+      $(obj).css('margin-top', (viewbox_height - view_height) + 'px')
+    )
+
   render: (content) ->
     if content
       # Trim leading and trailing whitespace
-      content = content.replace /^\s+|\s+$/g, ""
+      content = content.trim()
 
     if content
       @el.html(content)
@@ -74,3 +105,37 @@ class @Hinter
       @$('#previous-answer-0').css('display', 'inline')
     else
       @el.hide()
+    # Initialize the answer choice - remembers which answer the user picked on
+    # p2 when he submits a hint on p3.
+    @answer = ''
+    # Determine whether the browser supports CSS3 transforms.
+    styles = document.body.style
+    if styles.WebkitTransform == '' or styles.transform == ''
+      @go_to = @transform_go_to
+    else
+      @go_to = @legacy_go_to
+
+    # Make the correct wizard view show up.
+    hints_exist = @$('#hints-exist').html() == 'True'
+    if hints_exist
+      @go_to('p1')
+    else
+      @go_to('p2')
+
+  transform_go_to: (view_id) ->
+    # Switch wizard views using sliding transitions.
+    id_to_index = {
+      'p1': 0,
+      'p2': 1,
+      'p3': 2,
+    }
+    translate_string = 'translateX(' +id_to_index[view_id] * -1 * parseInt($('#' + view_id).css('width'), 10) + 'px)'
+    @$('.wizard-container').css('transform', translate_string)
+    @$('.wizard-container').css('-webkit-transform', translate_string)
+    @set_bottom_links()
+
+  legacy_go_to: (view_id) ->
+    # For older browsers - switch wizard views by changing the screen.
+    @$('.wizard-view').css('display', 'none')
+    @$('#' + view_id).css('display', 'block')
+    @set_bottom_links()
\ No newline at end of file

common/lib/xmodule/xmodule/tests/test_crowdsource_hinter.py

@@ -2,7 +2,7 @@
 Tests the crowdsourced hinter xmodule.
 """
 
-from mock import Mock
+from mock import Mock, MagicMock
 import unittest
 import copy
 
@@ -53,6 +53,7 @@ class CHModuleFactory(object):
     @staticmethod
     def create(hints=None,
                previous_answers=None,
+               user_submissions=None,
                user_voted=None,
                moderate=None,
                mod_queue=None):
@@ -85,17 +86,59 @@ class CHModuleFactory(object):
         else:
             model_data['previous_answers'] = [
                 ['24.0', [0, 3, 4]],
-                ['29.0', [None, None, None]]
+                ['29.0', []]
             ]
 
+        if user_submissions is not None:
+            model_data['user_submissions'] = user_submissions
+        else:
+            model_data['user_submissions'] = ['24.0', '29.0']
+
         if user_voted is not None:
             model_data['user_voted'] = user_voted
 
         if moderate is not None:
             model_data['moderate'] = moderate
 
-        descriptor = Mock(weight="1")
+        descriptor = Mock(weight='1')
+        # Make the descriptor have a capa problem child.
+        capa_descriptor = MagicMock()
+        capa_descriptor.name = 'capa'
+        descriptor.get_children = lambda: [capa_descriptor]
+
+        # Make a fake capa module.
+        capa_module = MagicMock()
+        capa_module.lcp = MagicMock()
+        responder = MagicMock()
+
+        def validate_answer(answer):
+            """ A mock answer validator - simulates a numerical response"""
+            try:
+                float(answer)
+                return True
+            except ValueError:
+                return False
+        responder.validate_answer = validate_answer
+
+        def compare_answer(ans1, ans2):
+            """ A fake answer comparer """
+            return ans1 == ans2
+        responder.compare_answer = compare_answer
+
+        capa_module.lcp.responders = {'responder0': responder}
+        capa_module.displayable_items = lambda: [capa_module]
+
         system = get_test_system()
+        # Make the system have a marginally-functional get_module
+
+        def fake_get_module(descriptor):
+            """
+            A fake module-maker.
+            """
+            if descriptor.name == 'capa':
+                return capa_module
+        system.get_module = fake_get_module
+
         module = CrowdsourceHinterModule(system, descriptor, model_data)
 
         return module
@@ -146,11 +189,13 @@ class VerticalWithModulesFactory(object):
 
     @staticmethod
     def next_num():
+        """Increments a global counter for naming."""
         CHModuleFactory.num += 1
         return CHModuleFactory.num
 
     @staticmethod
     def create():
+        """Make a vertical."""
         model_data = {'data': VerticalWithModulesFactory.sample_problem_xml}
         system = get_test_system()
         descriptor = VerticalDescriptor.from_xml(VerticalWithModulesFactory.sample_problem_xml, system)
@@ -226,6 +271,24 @@ class CrowdsourceHinterTest(unittest.TestCase):
         self.assertTrue('Test numerical problem.' in out_html)
         self.assertTrue('Another test numerical problem.' in out_html)
 
+    def test_numerical_answer_to_str(self):
+        """
+        Tests the get request to string converter for numerical responses.
+        """
+        mock_module = CHModuleFactory.create()
+        get = {'response1': '4'}
+        parsed = mock_module.numerical_answer_to_str(get)
+        self.assertTrue(parsed == '4')
+
+    def test_formula_answer_to_str(self):
+        """
+        Tests the get request to string converter for formula responses.
+        """
+        mock_module = CHModuleFactory.create()
+        get = {'response1': 'x*y^2'}
+        parsed = mock_module.formula_answer_to_str(get)
+        self.assertTrue(parsed == 'x*y^2')
+
     def test_gethint_0hint(self):
         """
         Someone asks for a hint, when there's no hint to give.
@@ -235,21 +298,36 @@ class CrowdsourceHinterTest(unittest.TestCase):
         mock_module = CHModuleFactory.create()
         json_in = {'problem_name': '26.0'}
         out = mock_module.get_hint(json_in)
+        print mock_module.previous_answers
         self.assertTrue(out is None)
-        self.assertTrue(['26.0', [None, None, None]] in mock_module.previous_answers)
+        self.assertTrue('26.0' in mock_module.user_submissions)
 
     def test_gethint_unparsable(self):
         """
-        Someone submits a hint that cannot be parsed into a float.
+        Someone submits an answer that is in the wrong format.
         - The answer should not be added to previous_answers.
         """
         mock_module = CHModuleFactory.create()
         old_answers = copy.deepcopy(mock_module.previous_answers)
-        json_in = {'problem_name': 'fish'}
+        json_in = 'blah'
         out = mock_module.get_hint(json_in)
         self.assertTrue(out is None)
         self.assertTrue(mock_module.previous_answers == old_answers)
 
+    def test_gethint_signature_error(self):
+        """
+        Someone submits an answer that cannot be calculated as a float.
+        Nothing should change.
+        """
+        mock_module = CHModuleFactory.create()
+        old_answers = copy.deepcopy(mock_module.previous_answers)
+        old_user_submissions = copy.deepcopy(mock_module.user_submissions)
+        json_in = {'problem1': 'fish'}
+        out = mock_module.get_hint(json_in)
+        self.assertTrue(out is None)
+        self.assertTrue(mock_module.previous_answers == old_answers)
+        self.assertTrue(mock_module.user_submissions == old_user_submissions)
+
     def test_gethint_1hint(self):
         """
         Someone asks for a hint, with exactly one hint in the database.
@@ -258,7 +336,11 @@ class CrowdsourceHinterTest(unittest.TestCase):
         mock_module = CHModuleFactory.create()
         json_in = {'problem_name': '25.0'}
         out = mock_module.get_hint(json_in)
-        self.assertTrue(out['best_hint'] == 'Really popular hint')
+        self.assertTrue('Really popular hint' in out['hints'])
+        # Also make sure that the input gets added to user_submissions,
+        # and that the hint is logged in previous_answers.
+        self.assertTrue('25.0' in mock_module.user_submissions)
+        self.assertTrue(['25.0', ['1']] in mock_module.previous_answers)
 
     def test_gethint_manyhints(self):
         """
@@ -271,18 +353,18 @@ class CrowdsourceHinterTest(unittest.TestCase):
         mock_module = CHModuleFactory.create()
         json_in = {'problem_name': '24.0'}
         out = mock_module.get_hint(json_in)
-        self.assertTrue(out['best_hint'] == 'Best hint')
-        self.assertTrue('rand_hint_1' in out)
-        self.assertTrue('rand_hint_2' in out)
+        self.assertTrue('Best hint' in out['hints'])
+        self.assertTrue(len(out['hints']) == 3)
 
     def test_getfeedback_0wronganswers(self):
         """
         Someone has gotten the problem correct on the first try.
         Output should be empty.
         """
-        mock_module = CHModuleFactory.create(previous_answers=[])
+        mock_module = CHModuleFactory.create(previous_answers=[], user_submissions=[])
         json_in = {'problem_name': '42.5'}
         out = mock_module.get_feedback(json_in)
+        print out
         self.assertTrue(out is None)
 
     def test_getfeedback_1wronganswer_nohints(self):
@@ -294,9 +376,7 @@ class CrowdsourceHinterTest(unittest.TestCase):
         mock_module = CHModuleFactory.create(previous_answers=[['26.0', [None, None, None]]])
         json_in = {'problem_name': '42.5'}
         out = mock_module.get_feedback(json_in)
-        print out['index_to_answer']
-        self.assertTrue(out['index_to_hints'][0] == [])
-        self.assertTrue(out['index_to_answer'][0] == '26.0')
+        self.assertTrue(out['answer_to_hints'] == {'26.0': {}})
 
     def test_getfeedback_1wronganswer_withhints(self):
         """
@@ -307,8 +387,7 @@ class CrowdsourceHinterTest(unittest.TestCase):
         mock_module = CHModuleFactory.create(previous_answers=[['24.0', [0, 3, None]]])
         json_in = {'problem_name': '42.5'}
         out = mock_module.get_feedback(json_in)
-        print out['index_to_hints']
-        self.assertTrue(len(out['index_to_hints'][0]) == 2)
+        self.assertTrue(len(out['answer_to_hints']['24.0']) == 2)
 
     def test_getfeedback_missingkey(self):
         """
@@ -319,7 +398,7 @@ class CrowdsourceHinterTest(unittest.TestCase):
             previous_answers=[['24.0', [0, 100, None]]])
         json_in = {'problem_name': '42.5'}
         out = mock_module.get_feedback(json_in)
-        self.assertTrue(len(out['index_to_hints'][0]) == 1)
+        self.assertTrue(len(out['answer_to_hints']['24.0']) == 1)
 
     def test_vote_nopermission(self):
         """
@@ -327,7 +406,7 @@ class CrowdsourceHinterTest(unittest.TestCase):
         Should not change any vote tallies.
         """
         mock_module = CHModuleFactory.create(user_voted=True)
-        json_in = {'answer': 0, 'hint': 1}
+        json_in = {'answer': '24.0', 'hint': 1, 'pk_list': json.dumps([['24.0', 1], ['24.0', 3]])}
         old_hints = copy.deepcopy(mock_module.hints)
         mock_module.tally_vote(json_in)
         self.assertTrue(mock_module.hints == old_hints)
@@ -339,19 +418,56 @@ class CrowdsourceHinterTest(unittest.TestCase):
         """
         mock_module = CHModuleFactory.create(
             previous_answers=[['24.0', [0, 3, None]]])
-        json_in = {'answer': 0, 'hint': 3}
+        json_in = {'answer': '24.0', 'hint': 3, 'pk_list': json.dumps([['24.0', 0], ['24.0', 3]])}
         dict_out = mock_module.tally_vote(json_in)
         self.assertTrue(mock_module.hints['24.0']['0'][1] == 40)
         self.assertTrue(mock_module.hints['24.0']['3'][1] == 31)
         self.assertTrue(['Best hint', 40] in dict_out['hint_and_votes'])
         self.assertTrue(['Another hint', 31] in dict_out['hint_and_votes'])
 
+    def test_vote_unparsable(self):
+        """
+        A user somehow votes for an unparsable answer.
+        Should return a friendly error.
+        (This is an unusual exception path - I don't know how it occurs,
+        except if you manually make a post request.  But, it seems to happen
+        occasionally.)
+        """
+        mock_module = CHModuleFactory.create()
+        # None means that the answer couldn't be parsed.
+        mock_module.answer_signature = lambda text: None
+        json_in = {'answer': 'fish', 'hint': 3, 'pk_list': '[]'}
+        dict_out = mock_module.tally_vote(json_in)
+        print dict_out
+        self.assertTrue(dict_out == {'error': 'Failure in voting!'})
+
+    def test_vote_nohint(self):
+        """
+        A user somehow votes for a hint that doesn't exist.
+        Should return a friendly error.
+        """
+        mock_module = CHModuleFactory.create()
+        json_in = {'answer': '24.0', 'hint': '25', 'pk_list': '[]'}
+        dict_out = mock_module.tally_vote(json_in)
+        self.assertTrue(dict_out == {'error': 'Failure in voting!'})
+
+    def test_vote_badpklist(self):
+        """
+        Some of the pk's specified in pk_list are invalid.
+        Should just skip those.
+        """
+        mock_module = CHModuleFactory.create()
+        json_in = {'answer': '24.0', 'hint': '0', 'pk_list': json.dumps([['24.0', 0], ['24.0', 12]])}
+        hint_and_votes = mock_module.tally_vote(json_in)['hint_and_votes']
+        self.assertTrue(['Best hint', 41] in hint_and_votes)
+        self.assertTrue(len(hint_and_votes) == 1)
+
     def test_submithint_nopermission(self):
         """
         A user tries to submit a hint, but he has already voted.
         """
         mock_module = CHModuleFactory.create(user_voted=True)
-        json_in = {'answer': 1, 'hint': 'This is a new hint.'}
+        json_in = {'answer': '29.0', 'hint': 'This is a new hint.'}
         print mock_module.user_voted
         mock_module.submit_hint(json_in)
         print mock_module.hints
@@ -363,7 +479,7 @@ class CrowdsourceHinterTest(unittest.TestCase):
         exist yet.
         """
         mock_module = CHModuleFactory.create()
-        json_in = {'answer': 1, 'hint': 'This is a new hint.'}
+        json_in = {'answer': '29.0', 'hint': 'This is a new hint.'}
         mock_module.submit_hint(json_in)
         self.assertTrue('29.0' in mock_module.hints)
 
@@ -373,13 +489,12 @@ class CrowdsourceHinterTest(unittest.TestCase):
         already.
         """
         mock_module = CHModuleFactory.create(previous_answers=[['25.0', [1, None, None]]])
-        json_in = {'answer': 0, 'hint': 'This is a new hint.'}
+        json_in = {'answer': '25.0', 'hint': 'This is a new hint.'}
         mock_module.submit_hint(json_in)
         # Make a hint request.
         json_in = {'problem name': '25.0'}
         out = mock_module.get_hint(json_in)
-        self.assertTrue((out['best_hint'] == 'This is a new hint.')
-                        or (out['rand_hint_1'] == 'This is a new hint.'))
+        self.assertTrue('This is a new hint.' in out['hints'])
 
     def test_submithint_moderate(self):
         """
@@ -388,7 +503,7 @@ class CrowdsourceHinterTest(unittest.TestCase):
         dict.
         """
         mock_module = CHModuleFactory.create(moderate='True')
-        json_in = {'answer': 1, 'hint': 'This is a new hint.'}
+        json_in = {'answer': '29.0', 'hint': 'This is a new hint.'}
         mock_module.submit_hint(json_in)
         self.assertTrue('29.0' not in mock_module.hints)
         self.assertTrue('29.0' in mock_module.mod_queue)
@@ -398,10 +513,20 @@ class CrowdsourceHinterTest(unittest.TestCase):
         Make sure that hints are being html-escaped.
         """
         mock_module = CHModuleFactory.create()
-        json_in = {'answer': 1, 'hint': '<script> alert("Trololo"); </script>'}
+        json_in = {'answer': '29.0', 'hint': '<script> alert("Trololo"); </script>'}
         mock_module.submit_hint(json_in)
+        self.assertTrue(mock_module.hints['29.0']['0'][0] == u'&lt;script&gt; alert(&quot;Trololo&quot;); &lt;/script&gt;')
+
+    def test_submithint_unparsable(self):
+        mock_module = CHModuleFactory.create()
+        mock_module.answer_signature = lambda text: None
+        json_in = {'answer': 'fish', 'hint': 'A hint'}
+        dict_out = mock_module.submit_hint(json_in)
+        print dict_out
         print mock_module.hints
-        self.assertTrue(mock_module.hints['29.0'][0][0] == u'&lt;script&gt; alert(&quot;Trololo&quot;); &lt;/script&gt;')
+        self.assertTrue('error' in dict_out)
+        self.assertTrue(None not in mock_module.hints)
+        self.assertTrue('fish' not in mock_module.hints)
 
     def test_template_gethint(self):
         """
@@ -409,7 +534,7 @@ class CrowdsourceHinterTest(unittest.TestCase):
         """
         mock_module = CHModuleFactory.create()
 
-        def fake_get_hint(get):
+        def fake_get_hint(_):
             """
             Creates a rendering dictionary, with which we can test
             the templates.

common/templates/hinter_display.html

@@ -3,94 +3,137 @@
 
 
 <%def name="get_hint()">
-    % if best_hint != '':
+    % if len(hints) > 0:
         <h4> Hints from students who made similar mistakes: </h4>
         <ul>
-        <li> ${best_hint} </li>
-    % endif
-    % if rand_hint_1 != '':
-        <li> ${rand_hint_1} </li>
-    % endif
-    % if rand_hint_2 != '':
-        <li> ${rand_hint_2} </li>
+        % for hint in hints:
+            <li> ${hint} </li>
+        % endfor
+        </ul>
     % endif
-    </ul>
 </%def>
 
 <%def name="get_feedback()">
-    <p><em> Participation in the hinting system is strictly optional, and will not influence your grade. </em></p>
-    <p>
-    Help your classmates by writing hints for this problem. Start by picking one of your previous incorrect answers from below:
-    </p>
+    <%
+    def unspace(in_str):
+        """
+        HTML id's can't have spaces in them.  This little function
+        removes spaces.
+        """
+        return ''.join(in_str.split())
+
+    # Make a list of all hints shown.  (This is fed back to the site as pk_list.)
+    # At the same time, determine whether any hints were shown at all.
+    # If the user never saw hints, don't ask him to vote.
+    import json
+    hints_exist = False
+    pk_list = []
+    for answer, pk_dict in answer_to_hints.items():
+        if len(pk_dict) > 0:
+            hints_exist = True
+        for pk, hint_text in pk_dict.items():
+            pk_list.append([answer, pk])
+    json_pk_list = json.dumps(pk_list)
+  %>
+
+  <!-- Tells coffeescript whether there are hints to show. -->
+  <span id="hints-exist" style="display:none">${hints_exist}</span>
+  <div class="wizard-viewbox"><div class="wizard-container">
+    <div class="wizard-view" id="p1">
+      <p>
+      <em> Optional. </em> Help us improve our hints!  Which hint was most helpful to you?
+      </p>
 
-    <div id="answer-tabs">
-        <ul>
-        % for index, answer in index_to_answer.items():
-            <li><a href="#previous-answer-${index}"> ${answer} </a></li>
-        % endfor
-        </ul>
+      <div id="pk-list" data-pk-list='${json_pk_list}' style="display:none"> </div>
 
-        % for index, answer in index_to_answer.items():
-        <div class = "previous-answer" id="previous-answer-${index}">
-        <div class = "hint-inner-container">
-            % if index in index_to_hints and len(index_to_hints[index]) > 0:
-                <p>
-                Which hint would be most effective to show a student who also got ${answer}?
-                </p>
-                % for hint_text, hint_pk in index_to_hints[index]:
-                    <p>
-                    <input class="vote" data-answer="${index}" data-hintno="${hint_pk}" type="button" value="Vote"/>
-                    ${hint_text}
-                    </p>
-                % endfor
-                <p>
-                Don't like any of the hints above?  You can also submit your own.
-                </p>
-            % endif
-            <p>
-            What hint would you give a student who made the same mistake you did?  Please don't give away the answer.
-            </p>
-            <textarea cols="50" class="custom-hint" id="custom-hint-${index}">
-What would you say to help someone who got this wrong answer?
-(Don't give away the answer, please.)
-            </textarea>
-            <br/><br/>
-            <input class="submit-hint" data-answer="${index}" type="button" value="submit">
-        </div></div>
-        % endfor
+      % for answer, pk_dict in answer_to_hints.items():
+          % for hint_pk, hint_text in pk_dict.items():
+              <p>
+              <input class="vote" data-answer="${answer}" data-hintno="${hint_pk}" type="button" value="Vote">
+              ${hint_text}
+              </p>
+          % endfor
+      % endfor
+
+      <p>
+      Don't like any of the hints above? 
+      <a class="wizard-link" dest="p2" href="javascript: void(0);">
+        Write your own!
+      </a></p>
     </div>
 
-    <p>Read about <a class="expand-goodhint" href="javascript:void(0);">what makes a good hint</a>.</p>
-    <div class="goodhint" style="display:none">
-      <h4>What makes a good hint?</h4>
+    <div class="wizard-view" id="p2">
+      % if hints_exist:
+        <p>
+        Choose the incorrect answer for which you want to write a hint:
+        </p>
+      % else:
+      <p>
+        <em>Optional.</em>  Help other students by submitting a hint!  Pick one of your previous
+        answers for which you would like to write a hint:
+      </p>
+      % endif
+      % for answer in user_submissions:
+          <a class="answer-choice" href="javascript: void(0)" value="${answer}">${answer}</a><br />
+      % endfor
+      % if hints_exist:
+        <p class="bottom">
+          <a href="javascript: void(0);" class="wizard-link" dest="p1"> Back </a>
+        </p>
+      % endif
 
-      <p>It depends on the type of problem you ran into. For stupid errors --
-      an arithmetic error or similar -- simply letting the student you'll be
-      helping to check their signs is sufficient.</p>
+    </div>
 
-      <p>For deeper errors of understanding, the best hints allow students to
-      discover a contradiction in how they are thinking about the
-      problem. An example that clearly demonstrates inconsistency or
-      <a href="http://en.wikipedia.org/wiki/Cognitive_dissonance" target="_blank"> cognitive dissonace </a>
-      is ideal, although in most cases, not possible.</p>
+    <div class="wizard-view" id="p3">
 
       <p>
-        Good hints either:
-        <ul>
-          <li> Point out the specific misunderstanding your classmate might have </li>
-          <li> Point to concepts or theories where your classmates might have a
-          misunderstanding </li>
-          <li> Show simpler, analogous examples. </li>
-          <li> Provide references to relevant parts of the text </li>
-        </ul>
+        Write a hint for other students who get the wrong answer of <span id="blank-answer"></span>.
       </p>
+      <p>Read about <a class="expand" data-target="goodhint" href="javascript:void(0);">what makes a good hint</a>.</p>
+
+      <textarea cols="50" class="custom-hint" data-answer="${answer}" style="height: 200px">
+Write your hint here.  Please don't give away the correct answer.
+      </textarea>
+      <br /><br />
+      <input class="submit-hint" data-answer="${answer}" type="button" value="Submit">
+      <div id="goodhint" style="display:none">
+        <h4>What makes a good hint?</h4>
+
+        <p>It depends on the type of problem you ran into. For stupid errors --
+        an arithmetic error or similar -- simply letting the student you'll be
+        helping to check their signs is sufficient.</p>
+
+        <p>For deeper errors of understanding, the best hints allow students to
+        discover a contradiction in how they are thinking about the
+        problem. An example that clearly demonstrates inconsistency or
+        <a href="http://en.wikipedia.org/wiki/Cognitive_dissonance" target="_blank"> cognitive dissonace </a>
+        is ideal, although in most cases, not possible.</p>
+
+        <p>
+          Good hints either:
+          <ul>
+            <li> Point out the specific misunderstanding your classmate might have </li>
+            <li> Point to concepts or theories where your classmates might have a
+            misunderstanding </li>
+            <li> Show simpler, analogous examples. </li>
+            <li> Provide references to relevant parts of the text </li>
+          </ul>
+        </p>
+
+        <p>Still, remember even a crude hint -- virtually anything short of
+        giving away the answer -- is better than no hint.</p>
+
+        <p>
+          <a href="http://www.apa.org/education/k12/misconceptions.aspx?item=2" target="_blank">Learn even more</a>
+        </p>
+      </div>
+      <p class="bottom">
+        <a href="javascript: void(0);" class="wizard-link" dest="p2"> Back </a>
+      </p>
+    </div>
+  <!-- Close wizard contaner and wizard viewbox. -->
+  </div></div>
 
-      <p>Still, remember even a crude hint -- virtually anything short of
-      giving away the answer -- is better than no hint.</p>
-
-      <p>
-        <a href="http://www.apa.org/education/k12/misconceptions.aspx?item=2" target="_blank">Learn even more</a>
-      </p>    </div>
 
 </%def>
 
@@ -124,6 +167,10 @@ What would you say to help someone who got this wrong answer?
     ${simple_message()}
 % endif
 
+% if op == "error":
+    ${error}
+% endif
+
 % if op == "vote":
     ${show_votes()}
 % endif

lms/djangoapps/instructor/hint_manager.py

 """
 Views for hint management.
 
-Along with the crowdsource_hinter xmodule, this code is still
-experimental, and should not be used in new courses, yet.
+Get to these views through courseurl/hint_manager.
+For example: https://courses.edx.org/courses/MITx/2.01x/2013_Spring/hint_manager
+
+These views will only be visible if MITX_FEATURES['ENABLE_HINTER_INSTRUCTOR_VIEW'] = True
 """
 
 import json
@@ -15,12 +17,17 @@ from mitxmako.shortcuts import render_to_response, render_to_string
 
 from courseware.courses import get_course_with_access
 from courseware.models import XModuleContentField
+import courseware.module_render as module_render
+import courseware.model_data as model_data
 from xmodule.modulestore import Location
 from xmodule.modulestore.django import modulestore
 
 
 @ensure_csrf_cookie
 def hint_manager(request, course_id):
+    """
+    The URL landing function for all calls to the hint manager, both POST and GET.
+    """
     try:
         get_course_with_access(request.user, course_id, 'staff', depth=None)
     except Http404:
@@ -28,24 +35,29 @@ def hint_manager(request, course_id):
         return HttpResponse(out)
     if request.method == 'GET':
         out = get_hints(request, course_id, 'mod_queue')
-        return render_to_response('courseware/hint_manager.html', out)
+        out.update({'error': ''})
+        return render_to_response('instructor/hint_manager.html', out)
     field = request.POST['field']
     if not (field == 'mod_queue' or field == 'hints'):
         # Invalid field.  (Don't let users continue - they may overwrite other db's)
         out = 'Error in hint manager - an invalid field was accessed.'
         return HttpResponse(out)
 
-    if request.POST['op'] == 'delete hints':
-        delete_hints(request, course_id, field)
-    if request.POST['op'] == 'switch fields':
-        pass
-    if request.POST['op'] == 'change votes':
-        change_votes(request, course_id, field)
-    if request.POST['op'] == 'add hint':
-        add_hint(request, course_id, field)
-    if request.POST['op'] == 'approve':
-        approve(request, course_id, field)
-    rendered_html = render_to_string('courseware/hint_manager_inner.html', get_hints(request, course_id, field))
+    switch_dict = {
+        'delete hints': delete_hints,
+        'switch fields': lambda *args: None,    # Takes any number of arguments, returns None.
+        'change votes': change_votes,
+        'add hint': add_hint,
+        'approve': approve,
+    }
+
+    # Do the operation requested, and collect any error messages.
+    error_text = switch_dict[request.POST['op']](request, course_id, field)
+    if error_text is None:
+        error_text = ''
+    render_dict = get_hints(request, course_id, field)
+    render_dict.update({'error': error_text})
+    rendered_html = render_to_string('instructor/hint_manager_inner.html', render_dict)
     return HttpResponse(json.dumps({'success': True, 'contents': rendered_html}))
 
 
@@ -165,7 +177,13 @@ def change_votes(request, course_id, field):
     Updates the number of votes.
 
     The numbered fields of `request.POST` contain [problem_id, answer, pk, new_votes] tuples.
-    - Very similar to `delete_hints`.  Is there a way to merge them?  Nah, too complicated.
+    See `delete_hints`.
+
+    Example `request.POST`:
+    {'op': 'delete_hints',
+     'field': 'mod_queue',
+      1: ['problem_whatever', '42.0', '3', 42],
+      2: ['problem_whatever', '32.5', '12', 9001]}
     """
 
     for key in request.POST:
@@ -193,6 +211,18 @@ def add_hint(request, course_id, field):
     problem_id = request.POST['problem']
     answer = request.POST['answer']
     hint_text = request.POST['hint']
+
+    # Validate the answer.  This requires initializing the xmodules, which
+    # is annoying.
+    loc = Location(problem_id)
+    descriptors = modulestore().get_items(loc, course_id=course_id)
+    m_d_c = model_data.ModelDataCache(descriptors, course_id, request.user)
+    hinter_module = module_render.get_module(request.user, request, loc, m_d_c, course_id)
+    if not hinter_module.validate_answer(answer):
+        # Invalid answer.  Don't add it to the database, or else the
+        # hinter will crash when we encounter it.
+        return 'Error - the answer you specified is not properly formatted: ' + str(answer)
+
     this_problem = XModuleContentField.objects.get(field_name=field, definition_id=problem_id)
 
     hint_pk_entry = XModuleContentField.objects.get(field_name='hint_pk', definition_id=problem_id)
@@ -214,6 +244,8 @@ def approve(request, course_id, field):
     hint list.  POST:
     op, field
     (some number) -> [problem, answer, pk]
+
+    The numbered fields are analogous to those in `delete_hints` and `change_votes`.
     """
 
     for key in request.POST:

lms/djangoapps/instructor/tests/test_hint_manager.py

@@ -2,6 +2,7 @@ import json
 
 from django.test.client import Client, RequestFactory
 from django.test.utils import override_settings
+from mock import patch, MagicMock
 
 from courseware.models import XModuleContentField
 from courseware.tests.factories import ContentFactory
@@ -137,16 +138,45 @@ class HintManagerTest(ModuleStoreTestCase):
         """
         Check that instructors can add new hints.
         """
+        # Because add_hint accesses the xmodule, this test requires a bunch
+        # of monkey patching.
+        hinter = MagicMock()
+        hinter.validate_answer = lambda string: True
+
         request = RequestFactory()
         post = request.post(self.url, {'field': 'mod_queue',
                                        'op': 'add hint',
                                        'problem': self.problem_id,
                                        'answer': '3.14',
                                        'hint': 'This is a new hint.'})
-        view.add_hint(post, self.course_id, 'mod_queue')
+        post.user = 'fake user'
+        with patch('courseware.module_render.get_module', MagicMock(return_value=hinter)):
+            with patch('courseware.model_data.ModelDataCache', MagicMock(return_value=None)):
+                view.add_hint(post, self.course_id, 'mod_queue')
         problem_hints = XModuleContentField.objects.get(field_name='mod_queue', definition_id=self.problem_id).value
         self.assertTrue('3.14' in json.loads(problem_hints))
 
+    def test_addbadhint(self):
+        """
+        Check that instructors cannot add hints with unparsable answers.
+        """
+        # Patching.
+        hinter = MagicMock()
+        hinter.validate_answer = lambda string: False
+
+        request = RequestFactory()
+        post = request.post(self.url, {'field': 'mod_queue',
+                                       'op': 'add hint',
+                                       'problem': self.problem_id,
+                                       'answer': 'fish',
+                                       'hint': 'This is a new hint.'})
+        post.user = 'fake user'
+        with patch('courseware.module_render.get_module', MagicMock(return_value=hinter)):
+            with patch('courseware.model_data.ModelDataCache', MagicMock(return_value=None)):
+                view.add_hint(post, self.course_id, 'mod_queue')
+        problem_hints = XModuleContentField.objects.get(field_name='mod_queue', definition_id=self.problem_id).value
+        self.assertTrue('fish' not in json.loads(problem_hints))
+
     def test_approve(self):
         """
         Check that instructors can approve hints.  (Move them

lms/templates/courseware/hint_manager.html → lms/templates/instructor/hint_manager.html

 <%inherit file="/main.html" />
 <%namespace name='static' file='/static_content.html'/>
-<%namespace name="content" file="/courseware/hint_manager_inner.html"/>
+<%namespace name="content" file="/instructor/hint_manager_inner.html"/>
 
 
 <%block name="headextra">

lms/templates/courseware/hint_manager_inner.html → lms/templates/instructor/hint_manager_inner.html

@@ -4,6 +4,7 @@
 <h1> ${field_label} </h1>
 Switch to <a id="switch-fields" other-field="${other_field}">${other_field_label}</a>
 
+<p style="color:red"> ${error} </p>
 
 % for definition_id in all_hints:
     <h2> Problem: ${id_to_name[definition_id]} </h2>
@@ -36,6 +37,7 @@ Switch to <a id="switch-fields" other-field="${other_field}">${other_field_label
     <br />
 % endfor
 
+<p style="color:red"> ${error} </p>
 <button id="hint-delete"> Delete selected </button> <button id="update-votes"> Update votes </button>
 
 % if field == 'mod_queue':