My son is eight and helps me weight out the malt and hops, crush the malt, etc. He seems to like helping out, in between playing with his Wii or reading.
A funny thing happened a couple weeks ago in his 2nd grade science class. They did an experiment where they added sugar to hot water, threw in some yeast, and put a balloon over the neck of the flask to capture CO2. At which point my son tells his teacher, "This is just like when me and my dad make beer." I'm so proud.