Tens and Ones
How many tens? How many ones? Then add them up.
Counting on in ones? Start here.
A short lesson on a number line, where one marker jumps ten at a time so you can see that every jump of ten is the same size. About about 4 minutes.
Show me jumps of ten →
How do jumps of ten work again?
For grown-ups
- How long: 10 to 15 minutes is plenty. Short and frequent beats long and occasional — the early-numeracy trials with the largest effects ran eight weeks or less.
- When they get one wrong: the page shows the working. Read it together rather than moving straight on. Feedback that explains is worth several times more than feedback that only marks right or wrong, and that gap is wider in maths than in any other subject.
- Not timed: thinking time is the point of a book. Let silences run.
- Print it too: doing the same problems on paper a few days later is worth more than doing twice as many today.
What this practises
Place value to 100 — reading a number as tens and ones, and adding without composing a new ten.
Place value before regrouping. This book stays deliberately inside the no-carry case, because a child who is still working out what the tens digit means cannot also be learning to carry — the two together overload working memory.
- The underlying idea
- Place value as composed units: ten ones become one ten.
- Where this sits in Illustrative Mathematics
- 1st grade Unit 4: Numbers to 99 · 1st grade Unit 5: Adding Within 100
- Sources
- Illustrative Mathematics / Kendall Hunt (2024) · Fyfe et al. (2014) all references →
Related measured skills: ALPACA · Early operations, CALF · Adding, no carry. What this means