## Lesson: Modeling and Recording AdditionDeveloping the Concept

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Once children have had practice adding 1 to numbers 0 through 9, you can introduce the concept of adding 2 to a number. Then you can focus on different ways to make a number, up to 10, include adding doubles.

Materials: overhead projector, 10 counters; Learning Tool 2 (Two-Part Mat), 10 counters, and Ways to Make (PDF file) worksheets for each child; Race to the Sum (PDF file) game board, spinner (0-4), number cubes (1-6) for every 2 children

Preparation: Be prepared to give each child 10 counters and a copy of Learning Tool 2 during the lesson. Prepare Ways to Make (PDF file) worksheets for each child. Make copies of Race to the Sum (PDF file) game boards and spinners with numbers 0-4 for each pair of children

Prerequisite Skills and Concepts: Children should be proficient in counting and recognizing numbers to 10. Children should show a good understanding of adding 1 to numbers 0 through 9.

• Say: We have learned how to add 1 to a number and how to write addition sentences.
Place 4 counters on the left side of the overhead and 1 on the right side.
• Ask: Who can tell me what addition sentence we can write?
Elicit from children the sentence 4 + 1 = 5.
• Ask: Which number is the total?
Children should say 5.
• Say: Another word for total is sum. The sum of 4 + 1 is 5.
• Ask: How many counters are on this side?
(Point to the left side.)
Children should say “4.”
• Ask: Now how many counters are on this side?
(Point to the right side.)
Children should say “2.”
• Say: Now let's count to find how many in all.
Children should count aloud to 6.
• Ask: How do we write this number sentence?
Elicit 4 + 2 = 6.
• Say: Four plus two equals six.
Write4 + 2 = 6 under4 + 1 = 5. Make sure the numbers and symbols are lined up.
• Practice adding 2 to various numbers through 8. Give each child 10 counters and a workmat and have them follow along. Model counting to find the sum. When children show an understanding of this, put 3 counters on each side of the overhead.
Children should say “3 + 3.”
• Say: Let's count to find the sum.
Children should count aloud to 6. Write3 + 3 = 6 on the overhead.
• Ask: What do you notice about the numbers on either side of the plus sign?
Children should say they are both 3 or they are both the same.
• Say: When you add the same number twice, you are doubling that number.
Write these number sentences on the overhead: 5 + 5; 3 + 1; 4 + 2; 1 + 1; 2 + 1; 2 + 2. Ask the children to identify the double facts.
• Say: Set aside 2 of the counters on your mat. Use the counters you have left to find which double fact has a sum of 8.
Give children time to work this out. Eventually someone should say “4 + 4.” Write4 + 4 = 8 on the board.
• Ask: What are some other ways to make 8? Use your counters if you need to.
Children should say that 7 + 1, 6 + 2, and 5 + 3 equal 8.
Write these sentences below 4 + 4 = 8, as shown below.
4 + 4 = 8
5 + 3 = 8
6 + 2 = 8
7 + 1 = 8
• Say: Let's look at all the different ways we found to make eight. Say the numbers as I point to them.
Have children count down each column from top to bottom saying “4, 5, 6, 7” and then “4, 3, 2, 1.”
• Ask: Do you see a pattern?
Children should say that each number in the first column is 1 more than the number above it. Children should say that each number in the second column is 1 less than the number above it. Distribute Ways to Make (PDF file) worksheets. Have children use the counters to find the double fact and write it on their worksheets. Then have them find and write the remaining number sentences for 10 on their worksheets.

Wrap-Up and Assessment Hints:
You can assign to each child or pair of children a number or set of numbers and have them model and write all the ways to make that number. You can assess children's understanding of addition by observing them as they play Race to the Sum. This game will assess their ability to add numbers to 10 and identify double facts. You may wish to have children record their addition sentences as they play.