Create a movie clip, dots movie. Insert an instance of the dot symbol into frame 1 and in frame 18. Modify the instance of the dot in frame 1 to Alpha 0 and scale it to 20% of its original size.

Modify the instance of the dot in frame 18 to Alpha 100.

Tween the two frames (with a motion tween). Testing the scene shows the dot changing from small and transparent to large and opaque.