In previous lessons, students learned that the digit on the left of a 2-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.

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.

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