I found about 20 objects around the house that had different shapes. (You'll see a few "mistakes" I made in a second.) I placed them onto a large piece of paper. [NOTE: I went to the local newspaper office and bought a huge roll of newspaper paper for $5.]
Then I traced the basic/rough outline of each object.
As you can see, the jar lid and the apple are both a similarly-sized circle. So those were confused when he was putting the objects back in place. Also, the large lego piece would have made more sense if I turned it to the side, so that the little nubs were visible. He left that one for the end because he couldn't figure it out (a rectangle isn't obviously a lego, you know?).
And here's a short video that shows the process. This is an activity we will do regularly! It would be easy to recreate using whatever objects fit our current theme, too. This one has no theme, but if we were learning about shapes, fruits and vegetables, or the continents, this would work nicely.