This is a great activity to trigger critical thinking skills in students of all ages, and to help justify their reasoning. I use this with my gifted students, and it can be extended by having students share their reasoning for their answers in small groups. No answer key is provided, as it is truly up to student interpretation and argumentation, but, my philosophy was: 1. starfish because it does not swim like a dolphin, shark or turtle 2. books because they are not a piece of furniture 3. comp