TEACHER EDITION

Tens and Ones

Grade 2 · Lesson 1 · Dimensions 2A p.5
Math Book 2 · sheet 1
Warm-up
This is the first lesson of the year — there is nothing behind it yet. Begin at the big idea.

What we are learning

A two-digit number is made of tens and ones, and the place a digit sits in tells you which it is.

How it is done — keep this beside you

These steps stay on your page while you work. If you get stuck, find the step you are on and read it again before you put your hand up.

1
Twenty-three counters, loose. Counting them one at a time is slow.
23 loose counters
2
I bundle ten.
23 loose counters [10] + 13 loose
3
I bundle ten more.
23 loose counters [10] + 13 loose [10] [10] + 3 loose
4
Two bundles and three left over.
23 loose counters [10] + 13 loose [10] [10] + 3 loose 2 tens 3 ones
5
I write it as a number. The 2 means two TENS.
23 loose counters [10] + 13 loose [10] [10] + 3 loose 2 tens 3 ones 23 = 2 tens 3 ones

Practice

I DOteacher builds it, nothing erased
How many tens and ones in 47?
  1. The 4 is in the tens place: 4 tens.
  2. The 7 is in the ones place: 7 ones.
  3. 47 = 4 tens 7 ones
WE DO 1together, on whiteboards
How many tens and ones in 62?
Tens first. Boards up.
  1. 6 tens 2 ones
WE DO 2together, on whiteboards
How many tens and ones in 30?
Watch the ones place carefully on this one.
  1. 3 tens 0 ones
YOU DOindependent, from the book
Book 2A p.5 — the Do section, clipped onto the slide
the book page
Ask yourself: “Which place is this digit sitting in?”
Watch for
30 is chosen for the zero. Children say '3 tens' and stop, because 0 ones feels like nothing to say. It must be said — it is what makes 30 different from 3.