When I talk with elementary school teachers about introducing the concept of supporting ideas with reasons and references to the text, I often get puzzled looks. This is understandable. Common Core, however, asks students to do this as young as third grade. This pedagogical shift away from just selecting a multiple choice response is daunting, but can be so rewarding for students. Teachers are thinking about how to answer the question: How do you know? Teachers need to probe students not to select the desired answer, but to add proof, support opinions, and interrogate text for how authors do the same. The Teaching Channel has a great 2 minute model that shows how to use sentence frames with elementary students.