Title – Decomposing Numbers-Addition

By – Cheryl Gelsomino

Primary Subject – Math

Grade Level – K-1

Unit: Decomposing numbers – Addition; displaying multiple ways to make the same number.

Duration: Approximately 40 minutes

Hook:

The teacher will begin by telling the students two number stories. The children will use paper plates on construction paper, with addition and equal signs on them. The teacher will model using a chart fashioned after the students’ board.

1. On Tuesday, I ate 4 pretzels for a snack, and 2 more pretzels at lunch. How many pretzels did I eat on Tuesday?

2. On Wednesday, I ate 3 pretzels for a snack, and 3 more pretzels at lunch. How many pretzels did I eat on Wednesday?

Outcomes:

• Students will be able to decompose a single digit number in order to know that numbers represent values.
  
• Students will be able to list various ways to make a number using double sided red/white disks.
  
• Students will be able to explain orally the various combinations they came up with while decomposing the number(s) given to them.

Essential question: How many different ways can you make the same number?

Understandings: Students will understand that

• 2 sets/numbers are added together to make one larger sum.
  
• There is more than one way to decompose a number.

Activities:

1. Each child will get a cup with the number 8 written on the outside, and 8 double sided discs inside.

2. The children will practice dumping out the discs in the cup, and exploring the various ways that the different combinations of red and white make 8.

3. After some time for exploration, the teacher will have each student give one combination for coming up with the number 8, and display it on large chart paper.

4. The teacher will then lead a discussion about the numerous ways the class decomposed the number 8.

5. The students will then be broken up into groups of 2 or 3.

6. Each group will be given a cup with a number on it. Each group will get a different number of disks to work with.

7. The students will take turns in their group finding, and recording, different combinations for decomposing the number they were given.

8. The teacher will walk around the room while the children are working in their groups to observe their progress. Based on these informal observations, the teacher will differentiate the next level of the activity.

9. (Depending on time, this step may be carried over to another day as an extension of the previous lesson). Each student will then be given their own sheet to work on, with varying numbers.

10. This activity can be differentiated in the following ways:

• To increase the difficulty: Give the student a bigger number to work with, and have them create more combinations for decomposing their number. Also, having the students find a missing addend would require higher order thinking as well. (Refer to higher differentiated activities 1 and 2)

• To decrease the difficulty: Give the students smaller numbers to work with; such as 3-7. Give the students number sentences where the sum is given, and have them fill in the number of red and white discs only. The aide will also be available for assistance if needed. (Refer to lower differentiated activity 1)

Checks for understanding:

• Teacher’s informal observations while students are working
  
• Students’ oral explanations of how they decomposed a given number.
  
• Record sheets with the combinations used to decompose a number.

Extension Activities:

Math Center and free choice activities

Everyday Math games such as:

Disappearing Train – Roll plus and minus dice to add or take away wheels from the train. You are finished once all the wheels are gone.

Dice game on wipe boards – Roll dice and write the addition sentence on the board with a buddy.

Domino Addition – Use dominos to create addition sentences.

Whole Group games: acting out number stories frequently

Extension Literature:

Cheerios Counting Book



One Bear All Alone

by Caroline Bucknall


How Many Veggies

by Phil Vischer


Bennies Pennies

by Pat Brisson


The Door Bell Rang

by Pat Hutchins

E-Mail

Cheryl Gelsomino

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