Create a new layer. To do this click on the "insert
layer"
button on the bottom left corner of the timeline. (see below)
Once you’ve created the new layer, rename the layer by double
clicking on the layer name, type “circle” then hit the Return key. Change the fill and line colors on the tool palette (near the bottom
of the tool palette) and draw a circle on the stage inside the rectangle.
Rename Layer 1 to "rectangle."
Now the timeline will show that both the circle layer and the rectangle
layer are visible for 25 frames.
Try this experiment:
Click on the empty white space below the layers (this ensures
that no frames are selected). Now press the F5 key. Notice that
this will add frames to both layers. If you had 20 layers, you would
be adding frames to all 20 layers. Add frames until both layers
reach 30 frames. If you’ve added too many frames, hold down
the shift key while pressing F5. This will remove frames.
Now click on one of the frames in the "circle" layer
- let’s say frame 12 (this will select the frame). Hold
down the shift key and press the F5 key. This
will remove frames from only the "circle" layer and not the rectangle
layer.
NOTE: When you remove or add frames, it happens on the right
side of the playhead.
Remove enough frames so that the circle layer ends at frame 25. Your
timeline should look like so:
When you play your movie, you should see the circle on top of the rectangle
until you reach frame 25, at which time the circle disappears.
Another experiment. You can see the circle on stage because it’s
layer is “on top of” the rectangle layer. If you wanted
to, you can rearrange your layers. Click on the the name of the "circle"
layer and drag downwards. While holding the mouse button, you will
see a
gray line that represents where the layer will go once you release
the mouse button. Release the mouse button so that the "circle"
layer is below the "rectangle" layer. When you
look at your stage, your circle will have disappeared.
In fact it hasn’t disappeared, it’s just that you can’t
see it because it is “behind” the rectangle. Move the
circle layer back on top.
