Buildcraft[1] and Industrialcraft[2] are also good for teaching automation, logistics, and resource management. For example, buildcraft+redpower will let you build a machine that digs a giant hole in the ground, smelts the ores, incinerates the useless cobble, and sorts everything into the proper chests for easy access.

[1]: http://www.mod-buildcraft.com/ [2]: http://wiki.industrial-craft.net/index.php?title=Main_Page

Redpower is fantastic! I built an 8 bit ALU with it and its so much more pleasant (and faster) to work with than the standard redstone