The homework comes back with 38 + 47 = 75. You ask your child to look again, and they fix it in two seconds: 85. They knew how to do it. They were simply in a hurry. Slips like this are frustrating for both of you, and telling a child to "be more careful" rarely helps, because it does not say what to do.
This article explains why these slips happen and gives children aged about 6 to 11 a few concrete ways to check a calculation, plus ideas for making checking a habit rather than a punishment.
Why children make slips
- Finishing feels like the goal. Many children see a page of sums as something to get through. Speed feels like success.
- Their head is full. While carrying a ten or remembering a step, a child can lose track of a digit or the sign.
- Copying goes wrong. A 6 becomes a 9, a 47 becomes 74, or a number lands in the wrong column.
- The sign is skipped. The child sees two numbers and adds them, even though the sign says take away.
- Nobody showed them how to check. "Check your work" is only useful if a child knows what checking looks like.
None of this means your child is lazy or "bad at maths". Slips happen to adults too. The difference is that adults have learned a few ways to catch them.
Before calculating: read the sign and guess roughly
Two tiny habits before starting prevent many slips:
- Point at the sign and say it. "Plus" or "take away". It takes one second and catches the most common mix-up.
- Make a rough guess. Round the numbers to make an easy sum: 38 + 47 is about 40 + 50, so the answer should be close to 90. An answer of 75 or 805 now looks wrong straight away.
Younger children can guess with simpler words: "Will the answer be bigger or smaller than the numbers we started with?"
After calculating: put the pencil down and check
When your child finishes, ask them to put the pencil down for a moment. Then try one of these checks. They do not need all of them: pick the one that suits the calculation.
| Check | How it works | Example |
|---|---|---|
| Compare with the guess | Is the answer close to the rough guess? | 38 + 47: guess about 90, answer 85. Close enough. |
| Work backwards | Undo the calculation and see if you get back to the start | 85 − 47 = 38, so 38 + 47 = 85 is right |
| Look at the last digit | The last digits alone tell you how the answer must end | 8 + 7 = 15, so 38 + 47 must end in 5 |
| Read the question again | Did I copy the numbers correctly and use the right sign? | The question says 47, did I write 74? |
Working backwards is especially useful: subtraction checks addition, addition checks subtraction, and later, multiplication checks division. Children also see that the operations are linked, which helps their understanding.
Turning checking into a habit
- Build in time to check. If the homework takes ten minutes, the last two are for checking. Finishing early is not the goal; finishing and checking is.
- Say "there is one mistake in this row". Instead of pointing at the wrong answer, tell your child how many mistakes there are and where to look roughly. Finding it themselves teaches much more than being shown.
- Play "catch my mistake". You do a few sums out loud or on paper and slip in a deliberate error. Your child's job is to catch you. Children love correcting adults, and they practise checking without any pressure.
- Keep a list of "my usual slips". Some children often forget to carry, others mix up 6 and 9. A short personal list ("check the carry", "check 6 and 9") makes checking quicker and more focused.
- Praise the check, not the speed. "You found that one yourself!" is worth saying more than "You were fast."
If you notice that your child makes many slips in every kind of task, not only maths, or that the slips get worse rather than better with practice, talk to their teacher, who sees them working in class every day.
Calm practice helps
Children check better when they are not afraid of being wrong. A child who feels judged often rushes to get it over with, or hides a mistake instead of looking for it.
In Dologi, a wrong answer is not marked in red: your child is simply invited to try again. That moment of looking at the puzzle once more, without a big fuss, is a small version of the same checking habit.
In short
- Slips are usually about rushing, not about understanding. "Be careful" does not help; concrete checks do.
- Before calculating: say the sign and make a rough guess.
- After calculating: put the pencil down, then compare with the guess, work backwards or look at the last digit.
- Make checking part of the task, play "catch my mistake", and praise your child for finding their own slips.
Read more: My child just guesses: teaching children to stop and check.