Examples of what pupils should know and be able to do
First with and then without a 1–100 grid:
- Count on in tens from 30; from 26.
- Count on in 40s from 30; from 27.
- Count back in 30s from 160; from 145.
Probing questions
If you count in tens from 42, which digit changes? Why doesn't the ones digit change?
If you were to start with 93 and count back in tens, what would be the smallest number you would reach on a 1–100 grid? Would 14 be one of the numbers you would say? Why not?
What do you notice when I subtract 10 from a number? Can you explain?
What if pupils find this a barrier?
Give pupils a 1–100 grid and ask them to start from 5 and chant all the numbers moving vertically downwards. What's the same and what is different about these numbers? Why?
Start at 92 and move vertically upwards. What's happening now?
Repeat for different numbers. Continue without the grids, counting on and back in tens and hundreds. Make this a regular feature of oral and mental starters for lessons.