 ExerciseWithScroll = React.createClass
   displayName: 'ExerciseWithScroll'
   mixins: [ScrollListenerMixin, ScrollTrackerParentMixin, ExerciseMixin]
-  wrapPartWithScrollTracker: (exerciseParts, part, index) ->
+  wrapPartWithScroll: (parts, exercisePart, index) ->
+    part = parts[index]
+
     scrollState =
       key: part.stepIndex
       questionNumber: part.questionNumber

  renderPart: (part, partProps) ->
    props = _.omit(@props, 'part', 'canOnlyContinue', 'footer', 'setScrollState', 'goToStep')

    <ExercisePart {...partProps} {...props} step={part} id={part.id} taskId={part.task_id}/>

  renderSinglePart: ->
    {parts, footer} = @props

      scrollState={scrollState}
      setScrollPoint={@setScrollPoint}
      unsetScrollPoint={@unsetScrollPoint}>
      {exercisePart}
    </ScrollTracker>

  render: ->
