Guide · strategy
The Make a Ten Strategy: How 8 + 5 Becomes 10 + 3
To make a ten, move part of one number across to fill the other up to 10. For 8 + 5: 8 needs 2 to make 10, and 5 is 2 and 3, so 8 + 5 = 10 + 3 = 13. Children need two things first: the pairs that make 10, and being able to split a small number into two parts.
Why it works so well
Adding to 10 is the easiest addition there is: 10 + 3 needs no working out. The strategy turns every fact that crosses 10 into two small steps a child already knows. It also keeps paying off. The same move handles 28 + 5 and 48 + 7 later on, which is why it's one of the strategies Common Core names for first grade (standard 1.OA.C.6, making ten). Learning it now pays back for years.
How to teach it on ten-frames
Use two ten-frames. Put 8 counters on the first and 5 on the second. Ask: how many spaces are left in the first frame? Two. Slide 2 counters across. Now you have one full frame and 3 more: 13. Do this many times with real counters before writing anything down. After a while, ask children to say what they'd move before they move it. Then take the frames away and ask them to imagine it. Our guide to ten-frames has more.
The same idea for subtraction
Going back through 10 works the same way. For 13 − 5: take 3 to get to 10, and then there are 2 more to take away, which leaves 8. On a ten-frame, that's one full frame and 3 extra: remove the extras first, then 2 from the full frame. Children who've made ten in addition usually pick this up quickly. See it on 13 − 5.
How to do it with Sumtown
- Practice the pairs that make 10 until they come quickly.
- Practice splitting small numbers with number bonds.
- Work through a few fact pages together, like 8 + 5 and 7 + 6, using the ten-frame picture.
- Play the full game. It brings in the facts that cross 10 once the pairs are secure.
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Questions people ask
Which number should you split?
Usually the smaller one, filling up the bigger one. That means less to move. 9 + 4 is 9 + 1 + 3.
Why can't my child just count on?
Counting on 5 or more is slow and easy to get wrong. It works, but it doesn't grow into anything, whereas making ten does.
An app is on its way
We're building a Sumtown app for iPhone with the parts that need a real app: offline play for car rides, a town map that remembers how far your child got, and a parent report on every fact. Until then, the whole game is free right here.
Coming soon on theApp Store