Unit 4, Lesson 20# Recognize and make use of part–whole relationships within tape diagrams when solving a variety of problem types.

EngageNY 60 min(s)

In this lesson, students solve "put together/take apart with addend unknown" and "add to with change unknown" word problems within 20. As they do so, they explore number relationships as they notice and discuss how the size of the boxes relates to the size of each part. For example, when adding 12 + 4, students notice that the part in their tape diagram that contains 12 is much longer than the part that contains 4. They also notice that, when adding 10 + 10, the two parts are the same size.