In the prior sections, you observed students using the Reasoning and Proof Standard, you explored your own reasoning strategies by solving problems with attribute blocks, and you reflected on ways to help young children develop their reasoning skills through pattern recognition and classification activities. Now that you are familiar with the Standard and some of its aspects, it's time for you to apply it while doing some mathematical problem solving of your own! The following activity can be used to help students develop reasoning skills through sorting and classification. As you work, think about questions you could use to help your students develop ways to explain their thinking.

  Consider a problem