Lesson 4

The purpose of this lesson is for students to add and subtract multiples of 10 from multiples of 10.

In the last lesson, students added and subtracted 10 from multiples of 10. In this lesson, students strengthen their understanding of place value by adding and subtracting multiples of 10 from multiples of 10 represented in various ways. In the first activity, students solve story problems in familiar contexts and represent their thinking in a way that makes sense to them. They make connections between different representations. In the second activity, students play a familiar game in which they choose two cards and decide whether to add or subtract the numbers. In the lesson synthesis, students connect addition and subtraction of tens to basic addition and subtraction facts.

Activity 1: How Many Are in the Bag?

In future lessons, students will add two-digit numbers to other two-digit numbers by adding tens to tens and ones to ones. How did the work of today's lesson help transition students from methods based on counting on or counting back by one to methods based on place value?