Lesson 13
Center Day 2
Lesson Purpose
The purpose of this lesson is for students to add and subtract within 20 and work with two-digit numbers.
Lesson Narrative
In the first activity, students choose between activities that offer practice working with two-digit numbers. In the second activity, students choose an activity to work on adding and subtracting within 20.
Learning Goals
Teacher Facing
- Add and subtract within 20.
- Add tens to two-digit numbers.
- Count and represent a collection.
Student Facing
- Let’s add and subtract and work with tens and ones.
Required Materials
Materials to Gather
Required Preparation
Activity 1:
- Gather materials from previous centers:
- Grab and Count, Stage 2
- Five in a Row, Stages 1–4
- Check It Off, Stages 1–3
Activity 2:
- Gather materials from previous centers:
- How Close, Stages 1 and 2
- Number Puzzles, Stages 1 and 2
- Shake and Spill, Stages 3–5
CCSS Standards
Lesson Timeline
| Warm-up | 10 min |
| Activity 1 | 20 min |
| Activity 2 | 20 min |
| Lesson Synthesis | 10 min |
Teacher Reflection Questions
As students worked together today, where did you see evidence of the mathematical community established over the course of the school year?