Kindergarten · K.OA.A.1 · K.OA.A.2

Kindergarten addition and subtraction

Kindergarten addition starts with real things: 3 toy cars and 2 more toy cars, put together and counted. This year your child learns to show adding and taking away with objects, fingers and drawings. By the end of the year, your child solves simple word problems with numbers up to 10.

What the standards say

The official Common Core wording, quoted exactly. The plain version follows.

K.OA.A.1 Represent addition and subtraction with objects, fingers, mental images, drawings, sounds (e.g., claps), acting out situations, verbal explanations, expressions, or equations.

K.OA.A.2 Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.

What it means, in plain words

Showing adding and taking away K.OA.A.1

Addition means putting groups together and finding how many there are in all. Subtraction means taking some away and finding how many are left. Addition in kindergarten is shown before it is written, with blocks, fingers, claps, drawings or by acting a story out.

Later in the year, your child writes what the objects show as an equation, a number sentence with an equals sign. The plus sign means put together and the minus sign means take away. A drawing of 3 cars and 2 more cars becomes $3 + 2 = 5$ .

There is more than one right way to show a problem. Fingers, circles in a drawing or a row of buttons all work, as long as the numbers match the story.

Your child should be able to:

Act out or show adding with objects, fingers or a drawing
Show taking away by removing objects or crossing them out in a drawing
Match a picture or a story to an equation like $3 + 2 = 5$
Explain in words what the plus sign and the minus sign mean

Example

Six birds sit on a fence. Two fly away. How can your child show this story?

Draw 6 circles in a row, one for each bird.
Cross out 2 circles for the birds that fly away.
Count the circles that are not crossed out: there are 4.
Write it as $6 - 2 = 4$ . Four birds are still on the fence.

Word problems within 10 K.OA.A.2

Kindergarten addition and subtraction stay small. Adding and subtracting within 10 means every number in the problem, and the answer, is 10 or less. Children solve these by counting objects or drawings. Quick recall of sums up to 5 comes near the end of the year.

Addition word problems in kindergarten tell a short story where things join: some frogs sit on a log and more hop on. Subtraction word problems tell a story where things leave or get used up. Your child hears the story, shows it with objects and counts to find the answer.

Words like "more" and "in all" often mean add, and words like "left" and "fly away" often mean take away. Still, it helps more to picture what happens in the story than to hunt for a key word.

Your child should be able to:

Solve addition word problems and subtraction word problems with numbers up to 10
Use objects or a drawing to find the answer
Add and subtract within 10 by counting
Tell whether a story is about joining or taking away

Example

There are 5 crackers on a plate. Someone puts 3 more on the plate. How many crackers are on the plate now?

More crackers join the plate, so this is addition.
Put out 5 crackers, then 3 more.
Count them all: 1, 2, 3, 4, 5, 6, 7, 8.
$5 + 3 = 8$ . There are 8 crackers on the plate.

Example

There are 9 bubbles. Six of them pop. How many bubbles are left?

The bubbles that pop are gone, so this is subtraction.
Draw 9 circles and cross out 6.
Count the circles that are not crossed out: there are 3.
$9 - 6 = 3$ . There are 3 bubbles left.

Where children usually get stuck

For a story where some birds fly away, your child adds the two numbers.
The child has learned that a word problem means doing something with its two numbers. Adding came first, so it is the first thing the child tries.
What helps. Act the story out with toys before anyone writes a number. Then ask: did the group get bigger or smaller?
Your child counts 8 crackers and gets 9, because one cracker got two numbers or was touched twice.
Saying the numbers and touching the objects have to happen at the same pace. At 5 years old, that match still slips.
What helps. Ask your child to touch each object slowly with one finger, one number per touch, and to move it aside once it is counted.
Your child knows that $2 + 3 = 5$ but counts again from the start for $3 + 2$ .
The child has not yet noticed that adding the same two groups in either order gives the same total.
What helps. Make a row of 2 red blocks and 3 blue blocks. Turn the row around so the blue ones come first, and ask how many there are now before counting.

Try four practice questions

Real kindergarten questions from our question bank, easiest first. Answer them right here, check each one, and see a worked solution for any question.

1Warm-up
James's picture and number sentence are below. Choose + or − to match the picture.
$\displaystyle 2 \underline{\phantom{00}} 3 = 5$
A
$\displaystyle +$
B
$\displaystyle -$
Show the answer and how to solve it
The plus sign + goes in the blank because the picture shows putting groups together. So $2 + 3 = 5$ .
1. 1Look at James's picture. There are 2 fish and 3 more fish next to them.
2. 2When two groups are put together, that is the same as adding. So this picture shows adding.
3. 3When you add, use the plus sign +. So James's number sentence is:
Common mistake. A common mistake is picking − when there are no X marks. Look at the picture — both groups of fish are still there, being put together.
The idea underneath. Pictures with two separated groups show put together — use +.
2On level
Liam saw 2 ducks at the pond. Then 4 more ducks swam over. How many ducks are there in all?
A
7
B
4
C
5
D
6
Show the answer and how to solve it
There are 6 ducks in all. Liam saw 2 ducks first, then 4 more swam over. $2 + 4 = 6$ .
1. 1Look at the picture. Count the ducks in the first group: 1, 2. There are 2 ducks.
2. 2Now count the ducks in the second group: 1, 2, 3, 4. There are 4 ducks.
3. 3Put the two groups together to find how many in all. $2 + 4 = 6$ . So there are 6 ducks in all.
Common mistake. A common mistake is counting only one of the two groups — like picking 4 because 4 ducks swam over — and forgetting to add the 2 ducks that were already there.
The idea underneath. Adding tells you how many in all when two groups come together. Count each group, then count them all together.
3On level
Look at the subtraction below.
$\displaystyle 6 - 1 = 5$
Which picture matches?
A
B
C
D
Show the answer and how to solve it
The picture with 6 strawberries and 1 crossed out matches the equation 6 − 1 = 5. Start with 6, take away 1, leaves 5.
1. 1The equation is 6 minus 1 equals 5. This means: start with 6, take away 1, and 5 are left.
2. 2Look for a picture that has 6 strawberries in all (the start). Then check that 1 of those strawberries are crossed out (taken away).
3. 3The matching picture has 6 strawberries with 1 crossed out, leaving 5 strawberries. This matches the equation 6 − 1 = 5.
Common mistake. A common mistake is mixing up the take-away number (1) with the number left (5). The picture must have 1 strawberry crossed out, not 5.
The idea underneath. A subtraction picture has three parts: how many you start with, how many are crossed out (taken away), and how many are left. Match all three to the numbers in the equation.
4Stretch
6 butterflies are resting on a flower.
2 more flutter in to join them.
Look at the story. How many are there now?
Show the answer and how to solve it
Answer. 8
There are $8$ butterflies in all. When new butterflies join the group, add the two groups together: $6 + 2 = 8$ .
1. 1Look at the pictures. The first picture shows 6 butterflies resting on a flower. The second picture shows 2 more butterflies fluttering in to join them.
2. 2When new butterflies join the group, both groups are still there. Put them together by adding to find how many in all.
3. 3Add the starting butterflies and the new butterflies:
Common mistake. A common mistake is answering with just one of the numbers from the story, like $6$ or $2$ . When new butterflies join the group, both groups are still there — add them together: $6 + 2 = 8$ .
The idea underneath. When more things join a group, add to find how many in all. The total is bigger than what you started with.