In, On, but no under...

Mom and I are participating in a shaping class and our lesson for the weekend was "IN" "ON" and "UNDER." Well, we mastered the in and on in less than 20 minutes with lots of fun. However, the under part does not work for us. Mom's legs are too short and I am too big. We tried it, but Mom fell over and I couldn't move so we had a good laugh and I gave her kisses for trying, but back to the drawing board on that one. I know she did not give up, she has been walking through the house saying "what could he get under?" I think I am in trouble...

Here are my "IN" and "ON"