If your three-year-old is anything like mine, you get asked, "What day is it?" about a million times a day. He got in the habit of asking when we had an advent calender for Christmas, but even though that is long gone, he can't give up the habit of knowing exactly what day it is. So I whipped up this simple chart, with a spinning wheel underneath to reveal the day of the week. (I drew a sun on Sunday. While my boy is starting to read, he's still not patient enough to sound out the words. Drawing a sun helps him differentiate between Saturday and Sunday a little easier.)
The hardest part was dividing the circle into 7 equal parts. That, and not having a brass brad to make the circle spin, so I used a piece of twine, knotted on the front and back and it works pretty well. Now my boy loves changing the day every morning. In fact, after I put up the chart, a couple hours went by and he inevitably asked again, "What day is it?" When I replied Wednesday, he cried, "It's STILL WEDNESDAY?!?" haha!
Tip: It drives my hubby crazy that the wheel spins to the left, so if you're making this, it might be good to switch up the circle so it spins clockwise.