Sliding Boxes
 
1. Open a graphic of choice or make one of your own.  I made one which is 241x300 in size.  I didn't want to make it too big for the lesson. You're welcome to use this one for you lesson as well, just right click and save as.
 
 
2.  Add a new raster layer and flood fill with a color/gradient/pattern that coordinates with your graphic.  I used a red gradient.  You can also add any effects or filters to your color at this point.  I added Noise>Gaussian>30>Monochrome checked.
 
3.  Now add a tube, text, anything you want to decorate your solid colored layer and then merge those with your colored layer.  You should only have 2 layers at this point--your graphic and your decorated color layer. 
 
4.  Next, go to your selection tool and lengthwise select the left half of your canvas.
 
 
In the layer palette, right click on your red layer and Promote Selection to Layer.  Then, go back to your red layer and delete.  Deselect.  You should now have 3 layers like below.
 
 
5.  At this point, if your graphic image is a background go to Layers>Promote Background Layer.  Then, go to Image>Canvas Size and add more width to your canvas.  My width was originally 241 and I'm expanding it to 500.  You do not need to change the canvas height at all. 
 
 
Now, Copy Merge and paste into AS.
 
6.  Next, we're going to slide the 2 halves of the top image apart to reveal the lower graphic.  Make your top layer active.  Go to Effects>Image Effects>Offset.  Use these settings:  Horizontal -10, Vertical 0, Wrap is checked.  This will move it over to the left.  Now, go to the middle layer and go to Offset again, but change Horizontal to 10.  That will move this one to the right.
 
 
 
Copy Merge and paste after current frame in AS.
 
 
7.  Continue to offset each side of the upper image equally until you have completely uncovered your lower graphic.  Remember to Copy Merge and Paste after current frame in AS after each set of offset movement.  If your final offset doesn't fit exactly to the edges of your lower graphic just manually move the pieces to fit.
 
 
I ended up with 12 frames in AS when I finished.
 
 
8.  Now, we need to close the pieces back together as well.  In AS, Select All and Copy.  Go to your last frame and Paste After Current frame.  Now I have 24 frames with the last 12 still selected.  Go to Animation>Reverse Frames.  This will Reverse only the frames that were selected, so now instead of opening the images are closing.
 
9.  Select All and set the frame properties to 20.  Now click on Frame 1 and set frame properties to 50.  Click on your middle 2 frames (these will be the frames that have the lower graphic fully exposed, mine are frames 12 and 13) and set each of their frame properties to 75.  Click on your last frame and set frame properties to 50.  Now, when you preview it should look something like this.
 
 
Have fun!
Mae