   initialize: ->
     @model.set timer: @model.get('duration')
     @listenTo @model, 'change:timer', @renderTimer
+    @listenTo @model, 'change:running', @renderPlayButton
 
-  # Starts a timer with the value stored in the model.
+  # Starts or pauses a timer with the value stored in the model.
   #
   # @param [jQuery.Event] event the click event
   #

  #
  renderTimer: =>
    @ui.timer.text @model.get('timer')

    if @running
      clearInterval @running
      delete @running
      @model.set 'running', false
    else
      @running = setInterval @tick, 1000
      @model.set 'running', true

  # Start editing the name of the timelet.
  #
