Three Engaging Decomposing Activities For Math Centers

We teach students that numbers can be broken down into parts (decomposing) and put together (composing). In kindergarten, students explore these concepts with numbers 5 and 10 and teen numbers, but the idea of decomposing numbers resurfaces as they move from different grade levels. When they get to first grade, they’ll learn about place value, and in third grade, they will decompose to add and subtract three-digit numbers.

Students need to decompose numbers to 10 in more than one way using pictures, diagrams like number bonds, and objects. They also need to find the number that makes the sum, or whole, when they have one part. We teach decomposing for several months, and I always run out of activities for them to do to practice this concept. So, I’m always looking for new ideas or twists to old activities that are low prep, active, engaging.

Here are three engaging decomposing activities.

Shake and Spill

Shake and Spill is one of my students’ favorite decomposing games. I use it every year because it is so effective! It accomplishes two goals: students decompose a number into parts, and they show the decomposition using pictures or writing an equation.

Put two-colored counters (the number you want them to decompose) and show them how GENTLY to shake and spill the counters on the table. They count how many yellow and how many red counters. They record it as a picture and number sentence.

Have students share their decomposition to create discourse around numbers.

Students decompose numbers using counters.

Build It and Break It: A Decomposing Activity

Build It and Break is my GO-TO decomposing game. I teach students that we will build a number (like 5) using cubes, and then we will break it into parts. They break their cubes into parts. And we have decomposed! But we are not done yet. I have them put the cubes back together, and a lightbulb goes off. 2 and 3 are the same as 5. We just broke it into two parts. Now, they begin to understand decomposing. They record how they broke the cubes into two parts and write a number sentence. This is also great for math discourse since students explain how they decompose a number. It’s the most effective decomposing game I use.

Number Bonds

Yes, I love number bonds. It’s one of the resources you could use to show decomposition without having students write a number sentence. I like them because number bonds are so visual! The big circle represents the whole, and the two smaller circles are the parts. Students shake the counters in the cup, shake it, and record.