What?! You mean I was supposed to be learning too?! While I'm not sure learning is a requirement for homeschooling parents, I'm not sure it's avoidable either. Just a few of the many things I have learned about due to homeschooling my kids are:

electromagnets
sending letters in Mesopotamia (clay letters and envelopes entrusted passing travelers)
just how many different styles of cursive there are
patience, patience, patience (Argh! I mean.. Oh bother)

What has everyone else learned?