Decompose 10

Students break the number 10 into two smaller parts in multiple ways, recording each decomposition with drawings, objects, or equations (e.g., 10 = 1 + 9, 10 = 2 + 8, 10 = 5 + 5). Mastery of all ways to make 10 is a key benchmark.

Try three of them

Real questions from this skill, graded here. No account, and nothing is saved.

Decompose 10

Kindergarten · Decomposing Numbers and Making 10 · question 1 of 3

0 of 12

12 rungs. A star at the top.

10 = 6 +

How it is taught

0:00 of 2:03

Ten can be split in many pairs.

The two parts add to ten.

Read it: 2 parts make 10

There are 10 crackers. 2 go on 1 tray and 8 on the other. 10 = 2 + 8.

Put some on tray 1: 2.
Count tray 2: 8.
Say it: 10 = 2 + 8.

Moving crackers to another tray does not change how many there are.

So 2 on one tray and 8 on the other are still 10.

10 can be split in many ways: 1 and 9 is another one.

A number is 2 parts put together.

Thinking some crackers are gone when they move to the other tray.

Count both trays. 2 and 8 make 10.

10 = 3 + ___ — 7. Count on from 3: 4, 5, 6, 7, 8, 9, 10. That is 7.

10 = 6 + 4

We have ten cookies to share with two friends. Let's see how we can split them!

Here are our ten cookies, all lined up in a row.

Let's count them together: one, two, three, four, five, six, seven, eight, nine, ten.

Sam wants six cookies. How many will be left for Lily?

These six cookies are Sam's. We can pull them to one side.

And these are Lily's. Let's count them: one, two, three, four!

So we can write it as a number sentence: ten equals six plus four.

There are lots of ways to make ten — like nine plus one, eight plus two, or five plus five!

Kindergarten · Breaking 10 into two parts

Six plus four makes ten. Great job decomposing ten!

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics

Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal: 1 star — one skill mastered, every rung of its ladder climbed
Climbing now: Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

More of the library

Every skill has a page

Practise this skill free

14 days of every skill, practice packets, Fluency sheets and up to four students. No card.

Start free