An example of the "Opacity" transform is shown here...this is a great resource for teachers and students.

I've decided to build my own little After Effects Visual Reference Library for when I'm teaching my motion graphics classes and post it here. This is in no way meant to replace the books out on the market when you are teaching...It's more of a visual complement to them.

There is an example of the opacity transform below that you can play.

Some helpful shortcuts when dealing with opacity( I'm doing these from a PC so the shortcuts might be different in some cases on a Mac...whenever it says CTRL switch that to CMND or Open Apple for the Mac )

T = Opacity
J = Previous Keyframe
K = Next Keyframe
Home = Beginning of Timeline
End = End of Timeline

A. Opacity Property
B. Amount of Opacity 0% = Invisible, 100% = Visible

If you would like to use the After Effects project below you can find it HERE

Opacity 0% = Invisible, 100% = Visible