When you want to click a specific thing on a slide to start an animation effect, use a trigger. Triggers give you specific click points for controlling animation, and are especially useful when you want several effects on a slide.
Trigger an animation effect to begin when you click it
On the ANIMATIONS tab, in the Advanced Animation group, click Animation Pane.
In the Animation Pane, select the animated shape or other object that you want to trigger to begin playing when you click it.
In the Advanced Animation group, click Trigger, point to On Click of, and then, select the object.