Adding and subtracting
Add and subtract one-digit and two-digit numbers to 20, including zero
What a learner can do afterwards
- Calculate 14 + 5 = 19
- Calculate 17 – 3 = 14
- Add or subtract 0 and explain the result stays the same
The lesson
Adding puts numbers together. The total grows. Subtracting takes some away. The total shrinks. You already know number bonds. Use them to add fast.
Try it together
Zoe has 8 crayons. She takes away 0 crayons. She still has 8 crayons. Zero never changes the number.
Good to know
Start with the bigger number. Count up or down from there. Number bonds help you add fast.
Adding grows a number, subtracting shrinks it, and zero never changes it.
Watch it
Where it sits
Learn first
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.