Objectives:

1. Students will be able to explain how to add two 2-digit numbers within 20.
2. Students will be able to demonstrate how to add two 2-digit numbers within 20.

Materials:

• Worksheets with various two 2-digit numbers within 20

Warm-up:

1. Can anyone tell me what adding two 2-digit numbers within 20 means? (Answer: Adding two 2-digit numbers within 20 means to take two numbers with two digits each, that are within the number 20 and add them together.)

Lesson:

1. To start off, I’m going to show you how to add two 2-digit numbers within 20. We’ll use the numbers 15 and 10 as our example. (Write 15 + 10 on the board)

2. To start, make sure that you have a number line in your head and point to each number as you add them together.So, first we have 15 + 10. (Point to 15 on the number line and indicate that you are adding 10 to it.) Then, add the numbers just like you are adding single digit numbers. 15+10 = 25 (Write 25 on the board).

3. Now I want you all to try doing this on your own. On your worksheet, I have given you various combinations of two 2-digit numbers within 20. Go ahead and try to work those out. Make sure to use the number line in your head as you do this. (Allow the students some time to work on the worksheet.)

4. (Once the students have finished, have them work in pairs to check each other’s work and then leads a class discussion afterwards to check understanding.)

Conclusion:

1. So, what did we learn today? (Answer: We learned how to add two 2-digit numbers within 20 using the number line.)

2. Does anyone have any questions or comments?

3. Great! That’s all for today. Everyone did a fantastic job.