The work in this lesson builds upon understandings from grade 1, where students add and subtract within 20 with different strategies. This is a chance to formatively assess how students find sums and differences in this range. Connecting cubes organized in towers of 10 and singles should be made available for students to use, but encourage students to use them only if they need them. By the end of grade 2, students must fluently add and subtract within 20.

Math Community
Before the lesson, explain to students that norms are expectations that help everyone in the room feel safe, comfortable, and productive doing math together. Offer an example, such as: “It may help us share our ideas as a whole class if we have the norm ‘Listen as others share their ideas.’” Tell students to think about norms that help everyone do math as they work today, and that you will record these norms during the Lesson Synthesis.

By the end of grade 2, students must be fluent with addition and subtraction within 20, including knowing all sums of 2 one-digit numbers by memory. What did you learn about your students during today’s activities that will help you prepare all students to meet this standard?