     # should take a location as an argument
     if cmd == 'get_next'
       @mock_cnt++
-      response =
-        success: true
-        problem_name: 'Problem 1'
-        num_left: 3
-        num_total: 5
-        prompt: 'This is a fake prompt'
-        submission: 'submission! ' + @mock_cnt
-        rubric: 'A rubric! ' + @mock_cnt
-        submission_id: @mock_cnt
-        max_score: 2 + @mock_cnt % 3
-        ml_error_info : 'ML accuracy info: ' + @mock_cnt
+      switch data.location
+        when 'i4x://MITx/3.091x/problem/open_ended_demo1'
+          response =
+            success: true
+            problem_name: 'Problem 1'
+            num_left: 3
+            num_total: 5
+            prompt: 'This is a fake prompt'
+            submission: 'submission! ' + @mock_cnt
+            rubric: 'A rubric! ' + @mock_cnt
+            submission_id: @mock_cnt
+            max_score: 2 + @mock_cnt % 3
+            ml_error_info : 'ML accuracy info: ' + @mock_cnt
+        when 'i4x://MITx/3.091x/problem/open_ended_demo2'
+          response =
+            success: true
+            problem_name: 'Problem 2'
+            num_left: 2
+            num_total: 5
+            prompt: 'This is a fake second problem'
+            submission: 'This is the best submission ever! ' + @mock_cnt
+            rubric: 'I am a rubric for grading things! ' + @mock_cnt
+            submission_id: @mock_cnt
+            max_score: 2 + @mock_cnt % 3
+            ml_error_info : 'ML accuracy info: ' + @mock_cnt
+        else
+          response = 
+            success: false
+          
 
     else if cmd == 'save_grade'
       console.log("eval: #{data.score} pts,  Feedback: #{data.feedback}")
       response =
-        @mock('get_next', {location})
+        @mock('get_next', {location: data.location})
     # get_problem_list
     # sends in a course_id and a grader_id
     # should get back a list of problem_ids, problem_names, num_left, num_total

    else if @state == state_grading
      @ml_error_info_container.html(@ml_error_info)
      @prompt_container.html(@prompt)
      @prompt_name_container.html("#{@prompt_name} (#{@num_left} / #{@num_total})")
      @submission_container.html(@submission)
      @rubric_container.html(@rubric)


      response = 
        success: true
        problem_list: [
          {location: 'i4x://MITx/3.091x/problem/open_ended_demo1', \
            problem_name: "Problem 1", num_left: 3, num_total: 5},
          {location: 'i4x://MITx/3.091x/problem/open_ended_demo2', \
            problem_name: "Problem 2", num_left: 1, num_total: 5}
        ]
    else
