Composing and Decomposing Numbers

Students practice adding three 2-digit numbers while leveraging their understanding of base 10 representation. This activity is designed for 3rd grade students.

By Desmos Classroom

This warm up and quick routine takes about 5-10 minutes and can be used in or outside of a Math block. It is designed to be flexibly implemented in your day! Today's Goals • Add within 150 using strategies based on place value and composition and decomposition of numbers. • Apply ideas of place value to use the numbers 1, 5, 10, 50 and 100 when creating a variety of numbers. • Language Goal: Explain how to add numbers using composition strategies. (Speaking and Listening) Prep Checklist • Click Present to show this activity to the class or a small group. • On the Warm-Up screen, delete the 100 card from the scale and then have students work in small groups to discuss how to balance the scale. As students share their ideas, add number cards to the scale. • On the Activity Screen, select the green number cards and click Randomize. Invite students to share ways they could use the orange number cards to balance the scale.