Have you ever noticed that homeschoolers (and afterschoolers, I'm sure) talk differently to their children than other people do? We talk to them about everything; we're always explaining and pointing out new things. Everything is an educational experience. I've noticed it a lot when I spend time with other homeschoolers.
I have never specifically taught fractions to Crumpet. We talk about them all the time though when cooking, sharing pieces of things, etc.
Today, I cut a sandwich into four pieces instead of two for a change. He mentioned that the pieces were squares, and I said "Yes, I made four pieces today." Crumpet said, "You mean four quarters, Mom!" And yesterday we were baking, and he knew how to make half a cup using a whole cup measure.
Apparently, all of my chatter has taught him the concept of fractions without any of the stress of looking at pie pieces on a workbook page.
I love homeschooling!
And, because I have no pictures of a quartered sandwich, here's one of Crumpet learning basic car maintenance...