Jane Jansen's (of Gabriel Knight fame) first game for Sierra is an excellent adventure game for any kid who's old enough to type.

As son of an ecologist Adam, you must help the dolphin Cetus save the sea from pollution and waste. Educational elements are ingeniously blended into gameplay, from the new "recycle" icon that gives points when the player uses it on recylable objects, to lots of environmental facts throughout the narrative that are interwoven with traditional inventory-based puzzles. Highly recommended.