Shape tweens are used when you want to change one shape into a different shape. This is best done on a one to one ratio, for example, to change one circle into one star. Also, simple shapes will give you results that are at least somewhat predictable. Using a shape tween on complex shapes will often yield surprising results. If you try to use a shape tween to make it look like a caterpillar is morphing into a butterfly, you will get a tangled mess in the middle.
Shape tweens work on objects, primitive objects, and merged shapes.
1. In Flash, create a new file by going to File | New (Ctrl/Cmd N). Select Flash File (ActionScript 3.0) and hit OK.
2. Double-click on Layer 1 and rename it Shape Tween.
3. Use any one of the drawing tools to create a shape or object of any size and color you want. Remember to keep it simple. For instance, create an oval by dragging the Oval tool on the stage.
4. Right-click/Ctrl-click on the key frame in the timeline and choose...