       scrollState={scrollState}
       setScrollPoint={@setScrollPoint}
       unsetScrollPoint={@unsetScrollPoint}>
-      {exerciseParts[index]}
+      {exercisePart}
     </ScrollTracker>
 
   render: ->

      return @renderSinglePart()

    exerciseParts = @renderMultiParts()
    exercisePartsWithScroll = _.map parts, _.partial @wrapPartWithScrollTracker, exerciseParts
    exerciseGroup = @renderGroup()
    footer ?= @renderFooter()


  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
