After the educational / learning program starts, there are a few ways you can try to get it to quit (or not start):
- Press command-Q.
- Look for an icon for the program in the dock at the bottom of the screen. Control-click on the icon and pick Quit.
- Press option-command-escape, select that application, and click Force Quit.
- Hold the shift key down while the computer boots.
If none of those work, other choices include booting the computer from a Mac OS X DVD and booting the computer in "target disk mode" while it's cabled to another Mac.
If you can tell us the name of the program and/or what kind of Mac it is, that might help narrow down the choices.