Teaching article
Regrouping changes the pieces, not the amount
Make an exchange visible before using a written calculation procedure.
Exchange a group of ten ones for one ten and compare the quantity before and after. The important observation is conservation of value, not simply remembering to move a mark into another written column.
Build fourteen single units. Exchange ten for one group. Check that the represented total is unchanged.
Check the exchange both ways
Check that exchanging pieces preserves quantity. The materials change form while the represented amount remains equal.
One ten-group and four ones still represent fourteen after the exchange.
A regrouping exchange does not create or remove quantity.
How was equal value preserved? Use pre-counted groups and adult support.
Resources
- Maths Puzzle Generator — Choose arithmetic or missing-number questions only when they match the number relationship being explored.
Further reading
Read next
- Addition starts with two quantities we can identify
- Subtraction as taking away: show the starting amount
- Arrays: see the repeated grouping in rows and columns
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