Block Stacking

I found three wooden blocks resting on the floor rug. They looked like neat little cubes, so I walked straight over to see what happens when they go on top of each other. I pushed one flat with both arms, then lifted the second one up. It gave a solid clack when it landed. The third block wobbled for a second and slid right off onto the soft carpet. That was pretty funny. I picked it up, set it back down, and this time it stayed completely upright.