MA 2.05Change Game (Exchanging)

1. 1

   Place on the rug 17 units, 13 tens, and 4 hundreds in loose piles.

2. 2

   Start with the units. Count them into rows; at ten, stop: 'Ten units. We can change them for one ten.'

3. 3

   Carry the ten units to the bank on the tray, exchange them for one ten bar, and place it with the tens.

4. 4

   Count the units left: 7. Place the card 7.

5. 5

   Count the tens, now 14. Exchange ten tens for one hundred; 4 tens remain. Place the card 40.

6. 6

   Count the hundreds, now 5. Place the card 500.

7. 7

   Stack the cards and read the number: 547.

8. 8

   State the rule: 'When we have ten of one kind, we change them for one of the next kind.'

What catches the child’s eye

• The trip to the bank to trade ten units for one ten bar
• A loose pile shrinking to a few neat beads in each category

Extensions, easiest to hardest

1. Include thousands in the pile.
2. Exchange the other way: one ten for ten units, one hundred for ten tens.
3. Child records the number formed on paper.