Tux Paint is a simple and entertaining drawing program geared towards young children. It has a simple interface, sound effects, and a cartoon character (Tux, the Linux penguin). Along with drawing brush strokes, lines and shapes, you can also enter text and place "rubber stamp" (or "sticker") images on the picture. Tux Paint is extensible, and could be useful in an educational environment (such as a grammar, elementary, or grade school). It's portable across numerous platforms, and runs well even on slower systems like the Pentium 133MHz.
"Tux, of Math Command" is an educational math tutorial game for elementary school level children. Like so many other Linux games, it stars Tux, the Linux Penguin. Players must answer math equations to shoot down comets which are falling towards their cities. It can run on Linux/UNIX, Win32, Mac, and BeOS.