Doesn't repeat recently used problems.

Fix bug with line segment drops getting rejected.
Progresses to next level once >, <, = problems
for a given level are solved correctly.

15 files changed, 307 insertions, 159 deletions

diff --git a/TODO b/TODO
index d849fa6..6137012 100644
--- a/TODO
+++ b/TODO
@@ -19,7 +19,7 @@ Compare3 Lesson
 + Display intersection between Shapes in a different color?  IntersectionObject maybe?
 - Mass comparison: fit into answer box.
 - Fix drawing of mass parallelopipeds (ThreeDObjects).
-+ Fix behavior of line segments (drops getting rejected).
+- Fix behavior of line segments (drops getting rejected).
 + Volume comparison: fit into answer box.
 + Amount comparison: fit into answer box (maybe make wider and reposition).
 + Amount comparison: refine appearance of object groups.
diff --git a/amountproblem.py b/amountproblem.py
index f2327dc..bea98cd 100644
--- a/amountproblem.py
+++ b/amountproblem.py
@@ -38,6 +38,8 @@ class AmountProblem(Problem):
         self.letter1 = letter1
         self.letter2 = letter2
         
+        self.problem_number = -1
+        
         self.generate_problem()
         self.show_problem()
         
@@ -74,11 +76,14 @@ class AmountProblem(Problem):
         original_position2_model = Vector(1000, 200)
         
         # The total number of problems.
-        n_problems = 8
+        self.n_problems = 8
         
         # Choose a random problem.
         shape_scheme = random.randrange(0,6)
-        problem_number = random.randrange(0,n_problems)
+        
+        # Choose a random problem.
+        while (self.problem_number in self.container.recently_used):
+            self.problem_number = random.randrange(0, self.n_problems)
         
         self.n_shape1 = 8
         self.n_shape2 = 7
@@ -94,35 +99,35 @@ class AmountProblem(Problem):
         #problem_number = 1
         #print "problem_number =", problem_number
     
-        if problem_number == 0:
+        if self.problem_number == 0:
             self.n_shape1 = 6
             self.n_shape2 = 6
             self.shape1_in_pair = False
-        elif problem_number == 1:
+        elif self.problem_number == 1:
             self.n_shape1 = 6
             self.n_shape2 = 6
             self.shape1_in_pair = True
-        elif problem_number == 2:
+        elif self.problem_number == 2:
             self.n_shape1 = 6
             self.n_shape2 = 5
             self.shape1_in_pair = False 
-        elif problem_number == 3:
+        elif self.problem_number == 3:
             self.n_shape1 = 6
             self.n_shape2 = 5
             self.shape1_in_pair = True
-        elif problem_number == 4:
+        elif self.problem_number == 4:
             self.n_shape1 = 4
             self.n_shape2 = 4
             self.shape1_in_pair = False
-        elif problem_number == 5:
+        elif self.problem_number == 5:
             self.n_shape1 = 4
             self.n_shape2 = 4
             self.shape1_in_pair = True
-        elif problem_number == 6:
+        elif self.problem_number == 6:
             self.n_shape1 = 4
             self.n_shape2 = 3
             self.shape1_in_pair = False
-        elif problem_number == 7:
+        elif self.problem_number == 7:
             self.n_shape1 = 4
             self.n_shape2 = 3
             self.shape1_in_pair = True
diff --git a/areaproblem.py b/areaproblem.py
index ca03632..bc3c6cc 100644
--- a/areaproblem.py
+++ b/areaproblem.py
@@ -35,6 +35,8 @@ class AreaProblem(Problem):
         self.letter1 = letter1
         self.letter2 = letter2
         
+        self.problem_number = -1
+        
         self.generate_problem()
         self.show_problem()
         
@@ -103,12 +105,6 @@ class AreaProblem(Problem):
         SMALL_IRREG_PENTAGON_SHAPE_2 = self.smaller(IRREG_PENTAGON_SHAPE_2)
         LARGE_IRREG_PENTAGON_SHAPE_2 = self.larger(IRREG_PENTAGON_SHAPE_2)
 
-        ## Choose two random letter to represent the two quantities
-        #letter1 = random.choice(['A', 'B', 'C', 'D', 'G', 'H', 'K', 'L', 'M', 'N', 'P', 'S', 'T'])
-        #letter2 = letter1
-        #while letter2 == letter1:
-        #    letter2 = random.choice(['A', 'B', 'C', 'D', 'G', 'H', 'K', 'L', 'M', 'N', 'P', 'S', 'T'])
-            
         # Standard initial positions for the shapes.
         upper_left_position = Vector(300, 300)
         lower_right_position = Vector(900, 400)
@@ -126,112 +122,113 @@ class AreaProblem(Problem):
             (0, math.pi/4), (math.pi/4, 0), (0, math.pi/4), (math.pi/4, 0), (0, 0), (math.pi/2, 0), (0, math.pi/2) ])
         
         # The total number of problems.
-        n_problems = 30
+        self.n_problems = 30
         
         # Choose a random problem.
-        problem_number = random.randrange(0,n_problems)
+        while (self.problem_number in self.container.recently_used):
+            self.problem_number = random.randrange(0, self.n_problems)
         
         # Uncomment to test a particular problem.
         #problem_number = 0
         
         # Define the various problems. 
-        if problem_number == 0:
+        if self.problem_number == 0:
             object1 = SQUARE_SHAPE
             object2 = LARGE_SQUARE_SHAPE
-        elif problem_number == 1:
+        elif self.problem_number == 1:
             object1 = SMALL_SQUARE_SHAPE
             object2 = SQUARE_SHAPE
-        elif problem_number == 2:
+        elif self.problem_number == 2:
             object1 = SQUARE_SHAPE
             object2 = SQUARE_SHAPE
             
-        elif problem_number == 3:
+        elif self.problem_number == 3:
             object1 = RECTANGLE_SHAPE
             object2 = LARGE_RECTANGLE_SHAPE
-        elif problem_number == 4:
+        elif self.problem_number == 4:
             object1 = SMALL_RECTANGLE_SHAPE
             object2 = RECTANGLE_SHAPE
-        elif problem_number == 5:
+        elif self.problem_number == 5:
             object1 = RECTANGLE_SHAPE
             object2 = RECTANGLE_SHAPE
             
-        elif problem_number == 6:
+        elif self.problem_number == 6:
             object1 = TRIANGLE_SHAPE
             object2 = LARGE_TRIANGLE_SHAPE
-        elif problem_number == 7:
+        elif self.problem_number == 7:
             object1 = SMALL_TRIANGLE_SHAPE
             object2 = TRIANGLE_SHAPE
-        elif problem_number == 8:
+        elif self.problem_number == 8:
             object1 = TRIANGLE_SHAPE
             object2 = TRIANGLE_SHAPE
             
-        elif problem_number == 9:
+        elif self.problem_number == 9:
             object1 = RT_ANGLE_TRAPEZOID_SHAPE
             object2 = LARGE_RT_ANGLE_TRAPEZOID_SHAPE
-        elif problem_number == 10:
+        elif self.problem_number == 10:
             object1 = SMALL_RT_ANGLE_TRAPEZOID_SHAPE
             object2 = RT_ANGLE_TRAPEZOID_SHAPE
-        elif problem_number == 11:
+        elif self.problem_number == 11:
             object1 = RT_ANGLE_TRAPEZOID_SHAPE
             object2 = RT_ANGLE_TRAPEZOID_SHAPE
          
-        elif problem_number == 12:
+        elif self.problem_number == 12:
             object1 = TRAPEZOID_SHAPE
             object2 = LARGE_TRAPEZOID_SHAPE
-        elif problem_number == 13:
+        elif self.problem_number == 13:
             object1 = SMALL_TRAPEZOID_SHAPE
             object2 = TRAPEZOID_SHAPE
-        elif problem_number == 14:
+        elif self.problem_number == 14:
             object1 = TRAPEZOID_SHAPE
             object2 = TRAPEZOID_SHAPE
          
-        elif problem_number == 15:
+        elif self.problem_number == 15:
             object1 = PARALLELOGRAM_SHAPE
             object2 = LARGE_PARALLELOGRAM_SHAPE
-        elif problem_number == 16:
+        elif self.problem_number == 16:
             object1 = SMALL_PARALLELOGRAM_SHAPE
             object2 = PARALLELOGRAM_SHAPE
-        elif problem_number == 17:
+        elif self.problem_number == 17:
             object1 = PARALLELOGRAM_SHAPE
             object2 = PARALLELOGRAM_SHAPE
            
-        elif problem_number == 18:
+        elif self.problem_number == 18:
             object1 = IRREG_TRIANGLE_SHAPE_1
             object2 = LARGE_IRREG_TRIANGLE_SHAPE_1
-        elif problem_number == 19:
+        elif self.problem_number == 19:
             object1 = SMALL_IRREG_TRIANGLE_SHAPE_1
             object2 = IRREG_TRIANGLE_SHAPE_1
-        elif problem_number == 20:
+        elif self.problem_number == 20:
             object1 = IRREG_TRIANGLE_SHAPE_1
             object2 = IRREG_TRIANGLE_SHAPE_1
             
-        elif problem_number == 21:
+        elif self.problem_number == 21:
             object1 = IRREG_QUADRIATERAL_SHAPE_1
             object2 = LARGE_IRREG_QUADRIATERAL_SHAPE_1
-        elif problem_number == 22:
+        elif self.problem_number == 22:
             object1 = self.smaller(SMALL_SQUARE_SHAPE)
             object2 = self.smaller(SQUARE_SHAPE)
-        elif problem_number == 23:
+        elif self.problem_number == 23:
             object1 = IRREG_QUADRIATERAL_SHAPE_1
             object2 = IRREG_QUADRIATERAL_SHAPE_1
     
-        elif problem_number == 24:
+        elif self.problem_number == 24:
             object1 = IRREG_QUADRIATERAL_SHAPE_2
             object2 = LARGE_IRREG_QUADRIATERAL_SHAPE_2
-        elif problem_number == 25:
+        elif self.problem_number == 25:
             object1 = self.larger(self.larger(IRREG_QUADRIATERAL_SHAPE_2))
             object2 = LARGE_IRREG_QUADRIATERAL_SHAPE_2
-        elif problem_number == 26:
+        elif self.problem_number == 26:
             object1 = IRREG_QUADRIATERAL_SHAPE_2
             object2 = IRREG_QUADRIATERAL_SHAPE_2
     
-        elif problem_number == 27:
+        elif self.problem_number == 27:
             object1 = IRREG_PENTAGON_SHAPE_1
             object2 = LARGE_IRREG_PENTAGON_SHAPE_1
-        elif problem_number == 28:
+        elif self.problem_number == 28:
             object1 = self.larger(LARGE_IRREG_PENTAGON_SHAPE_2)
             object2 = LARGE_IRREG_PENTAGON_SHAPE_2
-        elif problem_number == 29:
+        elif self.problem_number == 29:
             object1 = IRREG_PENTAGON_SHAPE_1
             object2 = IRREG_PENTAGON_SHAPE_1
 
diff --git a/compare3lesson.py b/compare3lesson.py
index e40a627..7bbeed5 100644
--- a/compare3lesson.py
+++ b/compare3lesson.py
@@ -66,6 +66,9 @@ class Compare3Lesson(ObjectArea):
         self.last_alphabetical_letter1 = 'A'
         self.last_alphabetical_letter2 = 'A'
         
+        self.problem_number = -1
+        self.recently_used = [-1, -1, -1, -1, -1, -1, -1, -1]
+        
         self.progress = ProgressObject(Vector(10, 700), 30)
         self.add_object(self.progress)
  
@@ -79,6 +82,10 @@ class Compare3Lesson(ObjectArea):
         self.moons_visible = False
         
         self.n_errors = 0
+        self.n_equals_problems_correct = 0
+        self.n_greater_than_problems_correct = 0
+        self.n_less_than_problems_correct = 0
+        
         
     #TODO- Put this code in the ShapeObjects themselves.
     def check_problem_solved(self):
@@ -138,9 +145,30 @@ class Compare3Lesson(ObjectArea):
             self.problem_type ='cutting'
         
         #print "... so self.problem_type is now: ", self.problem_type
+        
+        self.recently_used = []
+            
+        if self.problem_type == 'length':
+            n_problems = 18
+        elif self.problem_type == 'amount':
+            n_problems = 8
+        elif self.problem_type == 'mass':
+            n_problems = 9
+        elif self.problem_type == 'volume':
+            n_problems = 12
+        elif self.problem_type == 'cutting':
+            n_problems = 12
+        else:
+            n_problems = 30
+        
+        for i in range(0, n_problems - 3):
+            self.recently_used.append(-1)
+        
+        #print ""
+        #print "self.recently_used = ", self.recently_used
                 
         # Uncomment this to choose a particular problem type.   
-        #self.problem_type = 'amount'
+        #self.problem_type = 'length'
           
         if self.problem_type == 'length':
             self.problem = LengthProblem(self, self.color_scheme, (self.alphabetical_letter1, self.alphabetical_letter2) )
@@ -154,6 +182,15 @@ class Compare3Lesson(ObjectArea):
             self.problem = CuttingProblem(self, self.color_scheme, (self.alphabetical_letter1, self.alphabetical_letter2) )
         else:
             self.problem = AreaProblem(self, self.color_scheme, (self.alphabetical_letter1, self.alphabetical_letter2) )
+           
+        # Choose a random problem.
+        while (self.problem_number in self.recently_used):
+            self.problem_number = self.problem.problem_number
+            
+        #print "self.problem_number = ", self.problem_number  
+        self.recently_used.insert(0, self.problem_number)
+        self.recently_used.pop()  
+        #print "Now self.recently_used = ", self.recently_used
                
         self.answer = self.problem.find_answer()
         self.problem_solved_stage1()
@@ -205,6 +242,7 @@ class Compare3Lesson(ObjectArea):
             self.problem.shape2.calculate_bounds()
                 
     def pose_problem_stage2(self):
+        #print "pose_problem_stage2 called"
         self.stage = 2
         self.instructions.text = 'Show the result using line segments'
         #print "pose_problem_stage2: string to call find_answer"
@@ -341,12 +379,34 @@ class Compare3Lesson(ObjectArea):
         self.instructions.text = 'The ' + quantity_name + ' '  + self.letter1.symbol + ' is ' \
                                     + text + ' the ' + quantity_name  + ' ' + self.letter2.symbol
 
-        if (self.n_errors == 0):
+        if (self.n_errors == 0 and self.n_equals_problems_correct > 0 \
+                and self.n_greater_than_problems_correct > 0 and self.n_less_than_problems_correct > 0):
             self.level += 1
-            print "self.level is now:", self.level
+            #print "self.level is now:", self.level
+            self.recently_used = [-1, -1, -1, -1, -1, -1, -1, -1]
             self.progress.take_a_step()
+            self.n_equals_problems_correct = 0
+            self.n_greater_than_problems_correct = 0
+            self.n_less_than_problems_correct = 0
+        #else:
+        #    print ""
+        #    print "n_equals_problems_correct =", self.n_equals_problems_correct
+        #    print "n_greater_than_problems_correct =", self.n_greater_than_problems_correct
+        #    print "n_less_than_problems_correct =", self.n_less_than_problems_correct
         
         self.pose_next_problem_arrow()
+        
+    def increment_n_equals_problems_correct(self):
+        if self.n_errors == 0:
+            self.n_equals_problems_correct += 1
+    
+    def increment_n_greater_than_problems_correct(self):
+        if self.n_errors == 0:
+            self.n_greater_than_problems_correct += 1
+    
+    def increment_n_less_than_problems_correct(self):
+        if self.n_errors == 0:
+            self.n_less_than_problems_correct += 1
 
     def pose_next_problem_arrow(self):
         # Put it all in an answer box.
diff --git a/cuttingproblem.py b/cuttingproblem.py
index 2185c78..e846d62 100644
--- a/cuttingproblem.py
+++ b/cuttingproblem.py
@@ -62,6 +62,8 @@ class CuttingProblem(Problem):
         self.letter1 = letter1
         self.letter2 = letter2
         
+        self.problem_number = -1
+        
         self.generate_problem()
         self.show_problem()
         
@@ -126,10 +128,11 @@ class CuttingProblem(Problem):
         (original_angle1, original_angle2) = (0, 0)
         
         # The total number of problems.
-        n_problems = 12
+        self.n_problems = 12
         
         # Choose a random problem.
-        problem_number = random.randrange(0,n_problems)
+        while (self.problem_number in self.container.recently_used):
+            self.problem_number = random.randrange(0, self.n_problems)
         
         # Uncomment to test a particular problem.
         #problem_number = 0
@@ -138,76 +141,76 @@ class CuttingProblem(Problem):
         self.sub_shapes2_points = [ ]
        
         # Define the various problems. 
-        if problem_number == 0:
+        if self.problem_number == 0:
             object1 = SQUARE_SHAPE
             object2 = TRIANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(200, 0), Vector(0, 200) ], [ Vector(200, 0), Vector(200, 200), Vector(0, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(200, -200), Vector(200, 0) ], [ Vector(200, 0), Vector(200, -200), Vector(400, 0) ] ]
-        elif problem_number == 1:
+        elif self.problem_number == 1:
             object1 = LARGE_SQUARE_SHAPE
             object2 = TRIANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(250, 0), Vector(0, 250) ], [ Vector(250, 0), Vector(250, 250), Vector(0, 250) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(200, -200), Vector(200, 0) ], [ Vector(200, 0), Vector(200, -200), Vector(400, 0) ] ]
-        elif problem_number == 2:
+        elif self.problem_number == 2:
             object1 = SQUARE_SHAPE
             object2 = LARGE_TRIANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(200, 0), Vector(0, 200) ], [ Vector(200, 0), Vector(200, 200), Vector(0, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(250, -250), Vector(250, 0) ], [ Vector(250, 0), Vector(250, -250), Vector(500, 0) ] ]
             
-        elif problem_number == 3:
+        elif self.problem_number == 3:
             object1 = SQUARE_SHAPE
             object2 = RECTANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(100, 0), Vector(100, 200), Vector(0, 200) ], [ Vector(100, 0), Vector(200, 0), Vector(200, 200), Vector(100, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(200, 0), Vector(200, 100), Vector(0, 100) ], [ Vector(200, 0), Vector(400, 0), Vector(400, 100), Vector(200, 100) ] ]          
-        elif problem_number == 4:
+        elif self.problem_number == 4:
             object1 = SQUARE_SHAPE
             object2 = SMALL_RECTANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(100, 0), Vector(100, 200), Vector(0, 200) ], [ Vector(100, 0), Vector(200, 0), Vector(200, 200), Vector(100, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(175, 0), Vector(175, 75), Vector(0, 75) ], [ Vector(175, 0), Vector(350, 0), Vector(350, 75), Vector(175, 75) ] ]
-        elif problem_number == 5:
+        elif self.problem_number == 5:
             object1 = SQUARE_SHAPE
             object2 = LARGE_RECTANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(100, 0), Vector(100, 200), Vector(0, 200) ], [ Vector(100, 0), Vector(200, 0), Vector(200, 200), Vector(100, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(225, 0), Vector(225, 125), Vector(0, 125) ], [ Vector(225, 0), Vector(450, 0), Vector(450, 125), Vector(225, 125) ] ]
            
-        elif problem_number == 6:
+        elif self.problem_number == 6:
             object1 = PARALLELOGRAM_SHAPE
             object2 = TRIANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(200, 0), Vector(200, 200) ], [ Vector(200, 0), Vector(400, 200), Vector(200, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(200, -200), Vector(200, 0) ], [ Vector(200, 0), Vector(200, -200), Vector(400, 0) ] ]
-        elif problem_number == 7:
+        elif self.problem_number == 7:
             object1 = PARALLELOGRAM_SHAPE
             object2 = LARGE_TRIANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(200, 0), Vector(200, 200) ], [ Vector(200, 0), Vector(400, 200), Vector(200, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(250, -250), Vector(250, 0) ], [ Vector(250, 0), Vector(250, -250), Vector(500, 0) ] ]
-        elif problem_number == 8:
+        elif self.problem_number == 8:
             object1 = PARALLELOGRAM_SHAPE
             object2 = SMALL_TRIANGLE_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(200, 0), Vector(200, 200) ], [ Vector(200, 0), Vector(400, 200), Vector(200, 200) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(175, -175), Vector(175, 0) ], [ Vector(175, 0), Vector(175, -175), Vector(350, 0) ] ]
         
-        elif problem_number == 9:
+        elif self.problem_number == 9:
             object1 = TRAPEZOID_SHAPE
             object2 = RECTANGLE_2_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [  [ Vector(0, 0), Vector(0, 150), Vector(-150, 150) ], [ Vector(0, 0), Vector(150, 0), Vector(300, 150), Vector(0, 150) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(150,0), Vector(300, 150), Vector(0, 150)], [ Vector(300, 150), Vector(150, 150), Vector(150, 0) ] ]
-        elif problem_number == 10:
+        elif self.problem_number == 10:
             object1 = TRAPEZOID_SHAPE
             object2 = LARGE_RECTANGLE_2_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
             self.sub_shapes1_points = [ [ Vector(0, 0), Vector(0, 150), Vector(-150, 150) ], [ Vector(0, 0), Vector(150, 0), Vector(300, 150), Vector(0, 150) ] ]  
             self.sub_shapes2_points = [ [ Vector(0, 0), Vector(175,0), Vector(350, 175), Vector(0, 175)], [ Vector(175, 0), Vector(350, 175), Vector(175, 175) ] ]
-        elif problem_number == 11:
+        elif self.problem_number == 11:
             object1 = TRAPEZOID_SHAPE
             object2 = SMALL_RECTANGLE_2_SHAPE      
             (original_position1, original_position2) = ( Vector (250, 250), Vector(500, 600) )  
diff --git a/draggableobject.py b/draggableobject.py
index 360e30b..bdf2063 100644
--- a/draggableobject.py
+++ b/draggableobject.py
@@ -13,6 +13,9 @@
 # 
 # You should have received a copy of the GNU General Public License
 # along with Math.  If not, see <http://www.gnu.org/licenses/>.
+
+DEBUG = False
+
 from objectarea import Object
 from droptargetobject import DropTargetObject
 from vector import Vector
@@ -79,31 +82,48 @@ class DraggableObject(Object):
                     i += 1
                     if o.contains(self.get_bounds()) and not o.full:
                         o.hilite = True
-                        #print "DraggableObject: DropTarget's hilite set to True, queue draw"
+                        if DEBUG:
+                            print "DraggableObject: DropTarget's hilite set to True, queue draw"
                         o.queue_draw()
                     else:
                         o.hilite = False
-                        #print "DraggableObject: DropTarget's hilite set to False, queue draw"
+                        if DEBUG:
+                            print "DraggableObject: DropTarget's hilite set to False, queue draw"
                         o.queue_draw()
                     
             # End the drag.             
             elif event.type == gtk.gdk.BUTTON_RELEASE:
+                if DEBUG:
+                    print "DraggableObject: BUTTON_RELEASE"
                 self.dragged = False
+                
                 if self.container:
                     self.container.snap_to_grid(self)
                 
                 b = False
                 
                 #Check whether the drop is inside a drop target.
+                if DEBUG:
+                    print "DraggableObject: has ", len(self.drop_targets), "drop targets"
+                    
                 for o in self.drop_targets:
-                    if o.contains(self.get_bounds()):
+                    #if o.contains(self.get_bounds()):
+                    # Try this: 6/4/09
+                    if o.hilite:
                         b = True
+                        if DEBUG:
+                            print "DraggableObject: trying to call processDrop"
                         if o.processDrop(self):
                             return True
                     
                 if not b:
+                    if DEBUG:
+                        print "DraggableObject: not in a DropTarget"
                     o.hilite = False
                     self.drop_origin.reset()
+                else:
+                    if DEBUG:
+                        print "DraggableObject: IS in a DropTarget!"
                                   
         # If drag is not already in progress.
         elif self.contains_point(epos):
diff --git a/lengthproblem.py b/lengthproblem.py
index 9965233..3c503e4 100644
--- a/lengthproblem.py
+++ b/lengthproblem.py
@@ -35,6 +35,8 @@ class LengthProblem(Problem):
         self.letter1 = letter1
         self.letter2 = letter2
         
+        self.problem_number = -1
+        
         self.generate_problem()
         self.show_problem()
         
@@ -68,13 +70,7 @@ class LengthProblem(Problem):
         LENGTH_13 = [ Vector(0, 0), Vector(50, 0), Vector(50, 500), Vector(0, 500) ]
         LENGTH_14 = [ Vector(0, 0), Vector(50, 0), Vector(50, 525), Vector(0, 525) ]
         LENGTH_15 = [ Vector(0, 0), Vector(50, 0), Vector(50, 550), Vector(0, 550) ]
-
-        ## Choose two random letter to represent the two quantities
-        #letter1 = random.choice(['A', 'B', 'C', 'D', 'G', 'H', 'K', 'L', 'M', 'N', 'P', 'S', 'T'])
-        #letter2 = letter1
-        #while letter2 == letter1:
-        #    letter2 = random.choice(['A', 'B', 'C', 'D', 'G', 'H', 'K', 'L', 'M', 'N', 'P', 'S', 'T'])
-            
+     
         # Standard initial positions for the shapes.
         upper_left_position = Vector(300, 300)
         lower_right_position = Vector(900, 400)
@@ -92,75 +88,76 @@ class LengthProblem(Problem):
             (0, math.pi/4), (math.pi/4, 0), (0, math.pi/4), (math.pi/4, 0), (0, 0), (math.pi/2, 0), (0, math.pi/2) ])
         
         # The total number of problems.
-        n_problems = 18
+        self.n_problems = 18
         
         # Choose a random problem.
-        problem_number = random.randrange(0, n_problems)
+        while (self.problem_number in self.container.recently_used):
+            self.problem_number = random.randrange(0, self.n_problems)
         
         # Uncomment to test a particular problem.
-        #problem_number = 0
+        #problem_number = 3
        
         # Define the various problems. 
-        if problem_number == 0:
+        if self.problem_number == 0:
             object1 = LENGTH_1
             object2 = LENGTH_1
     
-        elif problem_number == 1:
+        elif self.problem_number == 1:
             object1 = LENGTH_3
             object2 = LENGTH_3
     
-        elif problem_number == 2:
+        elif self.problem_number == 2:
             object1 = LENGTH_5
             object2 = LENGTH_5
     
-        elif problem_number == 3:
+        elif self.problem_number == 3:
             object1 = LENGTH_1
             object2 = LENGTH_3
-        elif problem_number == 4:
+        elif self.problem_number == 4:
             object1 = LENGTH_2
             object2 = LENGTH_4
     
-        elif problem_number == 5:
+        elif self.problem_number == 5:
             object1 = LENGTH_7
             object2 = LENGTH_7
-        elif problem_number == 6:
+        elif self.problem_number == 6:
             object1 = LENGTH_3
             object2 = LENGTH_5
-        elif problem_number == 7:
+        elif self.problem_number == 7:
             object1 = LENGTH_4
             object2 = LENGTH_6
     
-        elif problem_number == 8:
+        elif self.problem_number == 8:
             object1 = LENGTH_5
             object2 = LENGTH_7
-        elif problem_number == 9:
+        elif self.problem_number == 9:
             object1 = LENGTH_6
             object2 = LENGTH_8
     
-        elif problem_number == 10:
+        elif self.problem_number == 10:
             object1 = LENGTH_9
             object2 = LENGTH_9
-        elif problem_number == 11:
+        elif self.problem_number == 11:
             object1 = LENGTH_7
             object2 = LENGTH_9
-        elif problem_number == 12:
+        elif self.problem_number == 12:
             object1 = LENGTH_8
             object2 = LENGTH_10
     
-        elif problem_number == 13:
+        elif self.problem_number == 13:
             object1 = LENGTH_9
             object2 = LENGTH_11
-        elif problem_number == 14:
+        elif self.problem_number == 14:
             object1 = LENGTH_10
             object2 = LENGTH_12
     
-        elif problem_number == 15:
+        elif self.problem_number == 15:
             object1 = LENGTH_11
             object2 = LENGTH_11
-        elif problem_number == 16:
+        elif self.problem_number == 16:
             object1 = LENGTH_11
             object2 = LENGTH_13
-        elif problem_number == 17:
+        elif self.problem_number == 17:
             object1 = LENGTH_0
             object2 = LENGTH_2
     
diff --git a/linesegmentdroptarget.py b/linesegmentdroptarget.py
index 82d6dfc..fd80510 100644
--- a/linesegmentdroptarget.py
+++ b/linesegmentdroptarget.py
@@ -19,6 +19,8 @@ from droptargetobject import DropTargetObject
 from linesegmentobject import LineSegmentObject

 from linesegmentmovableobject import LineSegmentMovableObject

 

+DEBUG = False

+

 class LineSegmentDropTarget(DropTargetObject):

     """Drop target which line segments can be dropped."""

 

@@ -41,6 +43,11 @@ class LineSegmentDropTarget(DropTargetObject):
         self.answer = 'equal'

 

     def draw(self, cr):

+        #cr.set_source_rgb(0, 1, 1)

+        #self_bounds_mn, self_bounds_mx = self.get_bounds()

+        #cr.rectangle(self_bounds_mn.x, self_bounds_mn.y, self_bounds_mx.x - self_bounds_mn.x, self_bounds_mx.y - self_bounds_mn.y)

+        #cr.fill()

+        

         cr.rectangle(self.pos.x, self.pos.y, self.size.x, self.size.y)

         

         cr.set_source_rgb(0, 0, 0)

@@ -63,7 +70,7 @@ class LineSegmentDropTarget(DropTargetObject):
         return i

             

     def get_bounds(self):

-        return self.pos - Vector (2, 2), self.pos + self.size

+        return self.pos - Vector(2,2), self.pos + self.size

         

     def contains(self, other_bounds):

         self_bounds_mn, self_bounds_mx = self.get_bounds()

@@ -78,10 +85,16 @@ class LineSegmentDropTarget(DropTargetObject):
             return False

         

     def processDrop(self, draggable_object):

-        #print "processDrop called on object at ", self.pos

+        if DEBUG:

+            print "LineSegmentDropTarget: processDrop called on object at ", self.pos

         

         if not isinstance(draggable_object, LineSegmentObject) and not isinstance(draggable_object, LineSegmentMovableObject):

+            if DEBUG:

+                print "LineSegmentDropTarget: not a LineSegmentMovableObject"

             return False

+        else:

+            if DEBUG:

+                print "LineSegmentDropTarget: IS LineSegmentMovableObject!"

         

         if self.full:

             self.drop_origin.reset()

@@ -113,14 +126,16 @@ class LineSegmentDropTarget(DropTargetObject):
             movable_object.selectable = True

             movable_object.drop_targets = self.drop_targets

             movable_object.drop_origin = self.drop_origin

-            self.container.add_object(movable_object)

+            if self.container:

+                self.container.add_object(movable_object)

             self.contents = movable_object

             self.full = True

             self.hilite = False

             self.queue_draw()

             

-            if self.drop_origin: 

-                self.container.select_object(self.drop_origin.line1)

+            if self.drop_origin:

+                if self.container:

+                    self.container.select_object(self.drop_origin.line1)

             

         else: 

             if draggable_object.length == 100:

@@ -155,7 +170,7 @@ class LineSegmentDropTarget(DropTargetObject):
         if not self.answer_correct() and self.all_drop_targets_full():

             self.reset_all_drop_targets()

             self.container.register_error()

-        elif self.answer_correct():  

+        elif self.answer_correct():

             self.container.selected_object = None

             self.freeze_drop_targets()

             self.container.finish_problem_stage2()

diff --git a/linesegmentmovableobject.py b/linesegmentmovableobject.py
index 30fbd10..b363878 100644
--- a/linesegmentmovableobject.py
+++ b/linesegmentmovableobject.py
@@ -13,6 +13,9 @@
 # 
 # You should have received a copy of the GNU General Public License
 # along with Math.  If not, see <http://www.gnu.org/licenses/>.
+
+DEBUG = False
+
 from objectarea import Object
 from draggableobject import DraggableObject
 from vector import Vector
@@ -26,6 +29,9 @@ class LineSegmentMovableObject(MovableObject):
 
     def __init__(self, pos, length, drop_targets, container):
         MovableObject.__init__(self)
+        
+        if DEBUG:
+            print "LineSegmentMovableObject: constructor called "
 
         self.pos = pos
         self.length = length
diff --git a/linesegmentobject.py b/linesegmentobject.py
index 71f17ba..c9a3647 100644
--- a/linesegmentobject.py
+++ b/linesegmentobject.py
@@ -13,6 +13,9 @@
 # 

 # You should have received a copy of the GNU General Public License

 # along with Math.  If not, see <http://www.gnu.org/licenses/>.

+

+DEBUG = False

+

 from objectarea import Object

 from draggableobject import DraggableObject

 from vector import Vector

@@ -40,7 +43,12 @@ class LineSegmentObject(DraggableObject):
         self.drop_targets = drop_targets

         self.container = container

     

-    def draw(self, cr):   

+    def draw(self, cr):

+        #cr.set_source_rgb(1, 0, 1)

+        #self_bounds_mn, self_bounds_mx = self.get_bounds()

+        #cr.rectangle(self_bounds_mn.x, self_bounds_mn.y, self_bounds_mx.x - self_bounds_mn.x, self_bounds_mx.y - self_bounds_mn.y)

+        #cr.fill()

+        

         cr.move_to(self.pos.x - 25, self.pos.y + self.length - self.line_segment_length)

         cr.line_to(self.pos.x + 25, self.pos.y+ self.length - self.line_segment_length)

         

diff --git a/massproblem.py b/massproblem.py
index 411321c..4499323 100644
--- a/massproblem.py
+++ b/massproblem.py
@@ -37,6 +37,8 @@ class MassProblem(Problem):
         self.letter1 = letter1
         self.letter2 = letter2
         
+        self.problem_number = -1
+        
         self.generate_problem()
         self.show_problem()
         
@@ -54,57 +56,59 @@ class MassProblem(Problem):
             (color1, color2) = random.choice([(Color.RED, Color.BLUE), (Color.BLUE, Color.RED)])
         
         # The total number of problems.
-        n_problems = 9      
+        self.n_problems = 9      
+        
         # Choose a random problem.
-        problem_number = random.randrange(0,n_problems)
+        while (self.problem_number in self.container.recently_used):
+            self.problem_number = random.randrange(0, self.n_problems)
         
         # Uncomment to test a particular problem.
         #problem_number = 0
        
         # Define the various problems.
-        if problem_number == 0:
+        if self.problem_number == 0:
             size1 = 'short'
             size2 = 'short'
             self.mass1 = 1
             self.mass2 = 2
-        elif problem_number == 1:
+        elif self.problem_number == 1:
             size1 = 'short'
             size2 = 'short'
             self.mass1 = 2
             self.mass2 = 1
-        elif problem_number == 2:
+        elif self.problem_number == 2:
             size1 = 'short'
             size2 = 'short'
             self.mass1 = 1
             self.mass2 = 1
             
-        elif problem_number == 3:
+        elif self.problem_number == 3:
             size1 = 'tall'
             size2 = 'short'
             self.mass1 = 1
             self.mass2 = 2  
-        elif problem_number == 4:
+        elif self.problem_number == 4:
             size1 = 'tall'
             size2 = 'short'
             self.mass1 = 2
             self.mass2 = 1 
-        elif problem_number == 5:
+        elif self.problem_number == 5:
             size1 = 'tall'
             size2 = 'short'
             self.mass1 = 1
             self.mass2 = 2
     
-        elif problem_number == 6:
+        elif self.problem_number == 6:
             size1 = 'tall'
             size2 = 'tall'
             self.mass1 = 1
             self.mass2 = 2  
-        elif problem_number == 7:
+        elif self.problem_number == 7:
             size1 = 'tall'
             size2 = 'tall'
             self.mass1 = 2
             self.mass2 = 1 
-        elif problem_number == 8:
+        elif self.problem_number == 8:
             size1 = 'tall'
             size2 = 'tall'
             self.mass1 = 1
diff --git a/movableobject.py b/movableobject.py
index e382901..91e308d 100644
--- a/movableobject.py
+++ b/movableobject.py
@@ -17,6 +17,8 @@ from objectarea import Object
 from droptargetobject import DropTargetObject
 from vector import Vector
 
+DEBUG = False
+
 import gtk, math
 
 class MovableObject(Object):
@@ -90,16 +92,22 @@ class MovableObject(Object):
         return boolean
         
     def on_mouse(self, event):
-        #print "MovableObject: on_mouse called)"
+        if DEBUG:
+            print "MovableObject: on_mouse called"
+        
         if not self.selectable:
-            #print "MovableObject: on_mouse returning because not selectable: ", self
+            if DEBUG:
+                print "MovableObject: not self.selectable"
             return
-        
-        #print "MovableObject: on_mouse continuing...:", self
-        
+        else:
+            if DEBUG:
+                print "MovableObject: IS self.selectable!"
+         
         epos = Vector(event.x, event.y)
             
-        #print "Movable Object: self.drag_type =", self.drag_type
+        if DEBUG:
+            print "MovableObject: self.drag_type =", self.drag_type
+                
         # Process in progress dragging, if active.
         if self.drag_type:
             if self.drag_type == 'rotate':
@@ -134,7 +142,10 @@ class MovableObject(Object):
                         o.queue_draw()
                                  
             elif event.type == gtk.gdk.BUTTON_RELEASE:
-                #print "movable object: BUTTON_RELEASE"
+                
+                if DEBUG:
+                    print "MovableObject: BUTTON_RELEASE: ", self
+                    
                 if self.container:
                     self.container.drag_object.dragged = False
                      
@@ -147,20 +158,39 @@ class MovableObject(Object):
                 #Check whether the drop is inside a drop target.
                 for o in self.drop_targets:
                     has_drop_target = True
-                    #print "movable object: has a drop target"
+                    
+                    if DEBUG:
+                        print "MovableObject: has a drop target"
+        
                     if o.contains(self.get_bounds()):
                         inside_drop_target = True
-                        #print "movable object: is inside target"
+                        if DEBUG:
+                            print "MovableObject: is inside target"
+                        
                         
                         #if not has_drop_target:
-                        #print "movable object: try to call processDrop"
+                        if DEBUG:
+                            print "MovableObject: try to call processDrop"
+                        
                         if o.processDrop(self):
-                            #print "movable object: finished calling processDrop"
+                            if DEBUG:
+                                print "MovableObject: finished calling processDrop"
                             return True
                     
                 self.drag_type = None
                 
-                if has_drop_target and not inside_drop_target :
+                if not has_drop_target:
+                    if DEBUG:
+                        print "MovableObject: No drop target"
+                else:
+                    if DEBUG:
+                        print "MovableObject: Has a drop target"
+                                 
+                if has_drop_target and not inside_drop_target:
+                    
+                    if DEBUG:
+                        print "MovableObject: has_drop_target and not inside_drop_target"
+                        
                     self.container.remove_object(self)
                     if self.drop_origin:
                         self.drop_origin.select_primary_object()
diff --git a/signsdroptarget.py b/signsdroptarget.py
index 938366c..6c2506e 100644
--- a/signsdroptarget.py
+++ b/signsdroptarget.py
@@ -127,7 +127,9 @@ class SignsDropTarget(DropTargetObject):
             movable_object.drop_targets = self.drop_targets

             movable_object.drop_origin = self.drop_origin

             

-            self.container.add_object(movable_object)

+            if self.container:   

+                self.container.add_object(movable_object)

+                

             self.contents = movable_object

             self.full = True

             self.hilite = False

@@ -143,6 +145,14 @@ class SignsDropTarget(DropTargetObject):
         elif self.answer_correct():

             self.container.selected_object = None

             self.freeze_drop_targets()

+            

+            if self.answer == 'greater':

+                self.container.increment_n_greater_than_problems_correct()     

+            elif self.answer == 'equal':

+                self.container.increment_n_equals_problems_correct()   

+            elif self.answer == 'less':

+                self.container.increment_n_less_than_problems_correct()   

+                

             self.container.finish_problem_stage3()

             

         if self.drop_origin:

diff --git a/volumeobject.py b/volumeobject.py
index 88599ff..8f4c3c4 100644
--- a/volumeobject.py
+++ b/volumeobject.py
@@ -22,10 +22,9 @@ import gtk, math
 class VolumeObject(MovableObject):

     """Quasi three-dimensional container object."""

     

-    def __init__(self, color, symbol, pos, height = 400, lower_radius = 50, upper_radius = 100):

+    def __init__(self, symbol, pos, height = 400, lower_radius = 50, upper_radius = 100):

         MovableObject.__init__(self)

 

-        self.color = color

         self.symbol = symbol

         

         self.height = height

diff --git a/volumeproblem.py b/volumeproblem.py
index 3299a2a..730f97f 100644
--- a/volumeproblem.py
+++ b/volumeproblem.py
@@ -36,6 +36,8 @@ class VolumeProblem(Problem):
         self.letter1 = letter1
         self.letter2 = letter2
         
+        self.problem_number = -1
+        
         self.generate_problem()
         self.show_problem()
         
@@ -49,27 +51,19 @@ class VolumeProblem(Problem):
         #self.pan2_position = Vector(725, 500)
 
     def generate_problem(self):     
-        # Choose two random colors.
-        (color1, color2) = random.choice([(Color.RED, Color.BLUE), (Color.BLUE, Color.RED), \
-            (Color.RED, Color.GREEN), (Color.GREEN, Color.RED), \
-            (Color.BLUE, Color.GREEN), (Color.GREEN, Color.BLUE)]) 
-
-        ## Choose two random letter to represent the two quantities
-        #letter1 = random.choice(['A', 'B', 'C', 'D', 'G', 'H', 'K', 'L', 'M', 'N', 'P', 'S', 'T'])
-        #letter2 = letter1
-        #while letter2 == letter1:
-        #    letter2 = random.choice(['A', 'B', 'C', 'D', 'G', 'H', 'K', 'L', 'M', 'N', 'P', 'S', 'T'])
-        
+    
         # The total number of problems.
-        n_problems = 3      
+        self.n_problems = 12
+        
         # Choose a random problem.
-        problem_number = random.randrange(0,n_problems)
+        while (self.problem_number in self.container.recently_used):
+            self.problem_number = random.randrange(0, self.n_problems)
         
         # Uncomment to test a particular problem.
         #problem_number = 0
        
         # Define the various problems. 
-        if problem_number == 0:
+        if self.problem_number == 0:
             # First volume is a cylinder.
             self.height1 = 230.0
             self.lower_radius1 = 75
@@ -83,7 +77,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
         
-        elif problem_number == 1:
+        elif self.problem_number == 1:
             # First volume is a cylinder.
             self.height1 = 230.0
             self.lower_radius1 = 75
@@ -97,7 +91,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(1.1 * volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
             
-        elif problem_number == 2:
+        elif self.problem_number == 2:
             # First volume is a cylinder.
             self.height1 = 230.0
             self.lower_radius1 = 75
@@ -111,7 +105,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(0.9 * volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
             
-        elif problem_number == 3:
+        elif self.problem_number == 3:
             # First volume is a cylinder.
             self.height1 = 200.0
             self.lower_radius1 = 90
@@ -125,7 +119,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
                    
-        elif problem_number == 4:
+        elif self.problem_number == 4:
             # First volume is a cylinder.
             self.height1 = 200.0
             self.lower_radius1 = 90
@@ -139,7 +133,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(1.1 * volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
                    
-        elif problem_number == 5:
+        elif self.problem_number == 5:
             # First volume is a cylinder.
             self.height1 = 200.0
             self.lower_radius1 = 90
@@ -153,7 +147,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(0.9 * volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
                    
-        elif problem_number == 6:
+        elif self.problem_number == 6:
             # First volume is a cylinder.
             self.height1 = 180.0
             self.lower_radius1 = 87
@@ -167,7 +161,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
             
-        elif problem_number == 7:
+        elif self.problem_number == 7:
             # First volume is a cylinder.
             self.height1 = 180.0
             self.lower_radius1 = 87
@@ -181,7 +175,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(1.1 * volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
             
-        elif problem_number == 8:
+        elif self.problem_number == 8:
             # First volume is a cylinder.
             self.height1 = 180.0
             self.lower_radius1 = 87
@@ -195,7 +189,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(0.9 * volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
             
-        elif problem_number == 9:
+        elif self.problem_number == 9:
             # First volume is a cone.
             self.height1 = 120.0
             self.lower_radius1 = 45
@@ -209,7 +203,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
             
-        elif problem_number == 10:
+        elif self.problem_number == 10:
             # First volume is a cone.
             self.height1 = 120.0
             self.lower_radius1 = 45
@@ -223,7 +217,7 @@ class VolumeProblem(Problem):
             self.height2 = self.calculate_height_for_equal_volume(1.1* volume1, self.lower_radius2, self.upper_radius2)
             volume2 = self.calculate_volume(self.height2, self.lower_radius2, self.upper_radius2)
             
-        elif problem_number == 11:
+        elif self.problem_number == 11:
             # First volume is a cone.
             self.height1 = 120.0
             self.lower_radius1 = 45
@@ -249,11 +243,11 @@ class VolumeProblem(Problem):
             
         # Switch the shapes half the time (so we get > as well as < problems).
         if random.choice([0,1]) == 0:
-            self.shape1 = VolumeObject(color1, self.letter1, original_position1, self.height1, self.lower_radius1, self.upper_radius1)
-            self.shape2 = VolumeObject(color2, self.letter2, original_position2, self.height2, self.lower_radius2, self.upper_radius2)
+            self.shape1 = VolumeObject(self.letter1, original_position1, self.height1, self.lower_radius1, self.upper_radius1)
+            self.shape2 = VolumeObject(self.letter2, original_position2, self.height2, self.lower_radius2, self.upper_radius2)
         else:
-            self.shape1 = VolumeObject(color1, self.letter2, original_position1, self.height1, self.lower_radius1, self.upper_radius1)
-            self.shape2 = VolumeObject(color2, self.letter1, original_position2, self.height2, self.lower_radius2, self.upper_radius2)
+            self.shape1 = VolumeObject(self.letter2, original_position1, self.height1, self.lower_radius1, self.upper_radius1)
+            self.shape2 = VolumeObject(self.letter1, original_position2, self.height2, self.lower_radius2, self.upper_radius2)
             
         self.faucet_object = FaucetObject(Vector(0, 100))
         self.container.add_object(self.faucet_object)