# Lesson 8

### Lesson Purpose

The purpose of this lesson is for students to practice addition and subtraction within 100 to build fluency.

### Lesson Narrative

In previous lessons, students composed and decomposed units to add and subtract within 1,000. Students considered which sums and differences within 100 were more or less difficult for them to find.

In this lesson, students develop fluency with adding and subtracting within 100. In the first activity, all students play a new “Heads Up” game to practice fluency. This version of the game “Heads Up: Make 20” is structured differently (groups of 3, different recording directions) from the game in Section A. In the second activity, students choose which center game from previous units to play based on what they know they need to practice. Spinners and cards can be reused if they were saved from previous units or new cards can be printed for the centers and stages recommended for this lesson.

The cool-down should be completed before the lesson synthesis so that students can share their responses during the lesson synthesis

• Representation
• MLR8

### Learning Goals

Teacher Facing

• Add and subtract within 100.

### Student Facing

• Let’s fluently add and subtract within 100.

### Required Materials

Materials to Gather

Materials to Copy

### Required Preparation

Activity 1:

• Create a set of cards from the blackline master for each group of 3.

Activity 2:

• Each group of 2 needs access to the cards used in the previous activity.
• Gather materials from previous centers:
• Five in a Row, Stage 6
• Target Numbers, Stages 35

### Lesson Timeline

 Warm-up 10 min Activity 1 15 min Activity 2 20 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

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