Today is rung 1 of 14 on this topic
Adding and subtracting within 20
Can do: Solves 8 + 7 and 15 − 6 by making ten or using known facts, not by counting one by one.
Why it matters
These are the facts every later calculation stands on. Fluency here is what stops a Grade 4 child from losing a long-division question to a slip in 13 − 7.
What it looks like when it's wobbly
Fingers for everything, long pauses, and answers that are one out — the signature of counting rather than knowing.
⏱️ Two-minute check
Ask 9 + 6, 8 + 7, 14 − 8, 13 − 5 out loud. Watch the hands and the time.
Solid looks like: Three of four within about three seconds each, with a strategy they can describe.
The full activity for this topic · 10 minutes
Make Ten First
- 1Build 8 + 7 on two ten-frames: eight in one, seven in the other.
- 2Move two across to fill the first frame. "Now it's 10 + 5. What's that?"
- 3Say the strategy every time: "I took two from the seven to make ten."
- 4Repeat with 9 + 4, 7 + 6, 8 + 5 — the ones where making ten pays.
- 5Play a fast round with cards: turn two, add them, first to say it wins.
If it's too hard
Practise the bonds to ten alone first — that's the machinery this strategy runs on.
If it's too easy
Subtraction by the same route: 15 − 8 becomes "take 5 to get to ten, then 3 more."
Say this
"Don't count them all. Take some across to make a ten first — ten plus anything is easy."