Lock controls for kids

This is a great program for kids. I'd like to have a password controlled lock that would prevent them from changing settings, opening additional programs (e.g.keep the program always on top), printing without my say-so, or otherwise changing settings. Then I could leave this program open, so they could use the program whenever they liked, without messing with other stuff on the computer. (Assume that the children are normal, well-behaved kids, not malevolent hacker-terrorists. The lock would not need to be hacker-proof.)