Unit 7, Lesson 7
Compose a Greater Unit
Grade 2
Preparation
Lesson Narrative
In previous lessons, students used their understanding of place value to add and subtract within 100, by composing and decomposing tens. Students learned that a hundred is a unit composed of 10 tens. They composed and decomposed hundreds to name the values of base-ten blocks.
In this lesson, the number choices and the use of base-ten blocks encourage students to look for ways to add by place and to anticipate where composing a unit might be needed before adding (MP7).
- Representation
None
- Explain (orally and using other representations) how to determine if a ten or a hundred will be composed when adding within 1,000.
- Explain (orally) strategies for adding a three-digit number and a two-digit number.
- Let’s add 3-digit numbers and compose tens or hundreds.
Required Preparation
- Create a set of cards from the blackline master so that each student will receive 1 card.
Teacher Reflection Questions
In previous lessons, students were encouraged to make sense of computation methods based on counting on by place that did not explicitly compose a ten or a hundred. How did students demonstrate their understanding of hundreds, tens, and ones as units in today’s lesson? What evidence have you seen from students that demonstrates an understanding of composing a hundred when adding?