Number bonds
Recall number bonds (addition and related subtraction facts) within 20
What a learner can do afterwards
- Quickly recall that 8 + 5 = 13
- Given 13 – 5, respond 8 using knowledge of related addition fact
- Know all pairs of single-digit numbers that sum to numbers up to 20
The lesson
You already know many number bonds. Every bond makes two facts. One is adding. One is subtracting. If 8 + 5 = 13, then 13 − 5 = 8.
Tap each star and count out loud.
Try it together
Ravi knows 8 + 5 = 13. His teacher asks 13 − 5. Ravi does not count. He just remembers the bond and says 8.
Good to know
Stuck on a subtraction fact? Turn it into addition. Ask what number, plus the one you took away, makes the whole.
Know the addition fact, and its subtraction fact comes free.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
Then practise
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.