Here's how to teach subtraction to kids: start by taking away real objects, then count back on a number line, then teach "think addition," where 9 - 6 becomes "6 plus what makes 9?" Fact families tie it all together. Keep sessions short, use the same words each time, and add games once a step feels easy.
The order below follows the Common Core State Standards from kindergarten to second grade. If your child's school uses different words, ask the teacher, so home and school sound the same.
Stay on each step until it feels easy, and go back a step whenever your child gets stuck.
The kindergarten standards describe subtraction as "taking apart and taking from." They list many ways to show it: objects, fingers, mental images, drawings, sounds such as claps, acting out situations and explaining in words.
Taking from: line up 7 crackers. Your child eats 2. "7 take away 2 leaves 5."
Taking apart: put 6 toy cars on the table, 4 red and the rest blue. "There are 6 cars and 4 are red. How many are blue?"
Act it out: 5 stuffed animals sit on the couch and 3 go to bed. How many are left?
Say the sentence every time, then write it once your child is ready: 7 - 2 = 5.
The first grade standards ask children to relate counting to addition and subtraction. For subtraction, the simplest link is counting back. For 12 - 3, start at 12 and say three numbers going down: "11, 10, 9." The answer is 9.
Counting back works well when the number taken away is small, such as 1, 2 or 3. For bigger take-aways it gets slow and easy to get wrong.
A US Department of Education practice guide on helping students who struggle with math recommends using the number line to teach math ideas. Make one on the floor with painter's tape, numbered 0 to 20.
Jump back: for 15 - 4, stand on 15 and hop back 4 times. Where did you land?
Find the gap: for 13 - 9, stand on 9 and hop forward to 13. Count the hops: 4. Subtraction can also tell you how far apart two numbers are.
The first grade standards say children should understand subtraction as an unknown-addend problem. Their example: subtract 10 - 8 by finding the number that makes 10 when added to 8. They also note that knowing 8 + 4 = 12 means you know 12 - 8 = 4.
So when your child sees 9 - 6, teach them to ask, "6 plus what makes 9?" This is where number bonds pay off. Our guides to number bonds to 10 and number bonds to 20 list every pair.
A fact family is a set of three numbers that make two addition facts and two subtraction facts. With 3, 5 and 8:
3 + 5 = 8
5 + 3 = 8
8 - 3 = 5
8 - 5 = 3
Draw a little house with the three numbers in the roof and the four facts in the windows.
For facts like 13 - 4, the first grade standards show a strategy that goes down to 10 first: 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9. Take away enough to land on 10, then take away the rest.
In second grade, children subtract within 100 and then within 1000, working with tens and ones and sometimes breaking a ten into ones. For 42 - 17, you can't take 7 ones from 2 ones, so trade one ten for 10 ones. Now you have 3 tens and 12 ones. Then 12 - 7 = 5, and 3 tens take away 1 ten leaves 2 tens. The answer is 25. Bundles of 10 straws make the trade something your child can hold.
Here's the Common Core path in plain English:
Kindergarten: solve simple word problems, add and subtract within 10 using objects or drawings, and subtract fluently within 5.
First grade: add and subtract within 20, with fluency within 10. Strategies include counting on, making ten, going down through 10 and using the link between addition and subtraction.
Second grade: add and subtract within 20 fluently using mental strategies, subtract fluently within 100, and subtract within 1000 using models or drawings.
Children move at different speeds. Treat the grades as a rough guide, not a deadline.
Bottle bowling: set up 10 empty plastic bottles and roll a ball. Count the bottles still standing and say the fact: "10 take away 4 is 6."
Bears in the cave: put 8 small toys on the table. While your child looks away, hide some under a bowl. They count the toys still showing and work out how many are hiding. This is think addition in disguise.
Hop back: on your floor number line, call out a start and a jump, like "Start on 14, hop back 5."
Difference war: take the picture cards out of a deck. Each player flips two cards and subtracts the smaller from the larger. The bigger difference wins the cards.
Beat your score: the same practice guide recommends regular timed activities, usually 1 to 5 minutes, as one way to build fluency. Try one friendly minute of fact cards, beating your own score. Skip the timer if it causes stress.
Counting the starting number. For 12 - 3, a child may say "12, 11, 10" and answer 10. Show that you start on 12 and count the jumps after it.
Flipping digits in bigger problems. In 42 - 17, some children take 2 from 7 instead of trading a ten, and get 35. Build it with bundles to show why the answer is 25.
Thinking subtraction only means take away. The first grade standards include comparing problems too, like "Sam has 9 stickers and Mia has 6. How many more does Sam have?"
Mixed-up words. The practice guide recommends clear, concise math language and suggests "regrouping" instead of "borrowing." Pick your words and use them every time.
Regrouping every problem. Once regrouping is introduced, the guide suggests mixing in problems that don't need it, so children don't apply it everywhere.
Start with real objects and simple stories where something is taken away. Then move to counting back for small numbers, then to think addition.
Under the Common Core, subtraction starts in kindergarten, usually age 5 to 6 in the US, with objects and drawings within 10. Fluency within 10 is a first grade goal, and fluency within 20 using mental strategies is a second grade goal.
Both are useful. Counting back is quick when only a little is taken away, like 15 - 2. Counting up is quicker when the numbers are close together, like 15 - 13: start at 13 and count up 2.
Tie every subtraction fact to an addition fact your child already knows, using fact families. Practice a few minutes a day with games, and add short, gentle timed rounds once the strategies make sense.
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Common Core State Standards: Kindergarten, Operations and Algebraic Thinking
Common Core State Standards: Grade 1, Operations and Algebraic Thinking
Common Core State Standards: Grade 2, Operations and Algebraic Thinking
Common Core State Standards: Grade 2, Number and Operations in Base Ten