Lesson 8

The purpose of this lesson is for students to interpret base-ten representations of two-digit numbers.

In previous lessons, students learned that the digit on the left of a two-digit number tells the number of tens and the digit on the right tells the number of ones.

In this lesson, students interpret three different base-ten representations: base-ten diagrams, _____ tens _____ ones, and addition expressions that represent the value of each digit. This is the first time students see expressions representing two-digit numbers other than 10 + n expressions representing teen numbers. Students match representations that show the same value.

At this time, students are not expected to write two-digit numbers, but continue to make sense of how to read and say them based on their base-ten structure. The teacher should record two-digit numbers when students say them.

Activity 1: Compare Representations of a Collection

• Create a set of cards from the blackline master for each group of 2–4.

What was the best question you asked students today? Why would you consider it the best one based on what students said or did?