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Trading with Tens Trading games provide the opportunity for students to bundle groups of ten in the case of adding, and to decompose groups of ten in the case of subtracting. A trading game follows one simple rule: nine objects may live in a particular place but not ten of them.

Consider the following scenario where 8 sticks are sitting on a Place Value Mat. This would represent 8 ones.

Tens

Ones

Tens

Ones

If five more ones are added to this group of eight sticks, the rule that only nine objects may live in one place would be violated.

The solution is to bundle ten of the sticks to make 1 ten. The bundle of sticks is moved one place to the left (i.e into the Tens column).

Tens

Base Ten Blocks

Ones

10

Š P. Swan

Eventually more and more tens are bundled until 9 bundles of ten fill a place. If another bundle is put in that place it will violate the rule that only 9 objects may live in a place.

Tens

Ones

The solution is to move one more place to the left, i.e into the Hundreds Place, and so on.

Hundreds

Tens

Ones

The students will learn that 10 tens make 100.

The reverse occurs when there is a need to take away sticks. If there are not enough sticks, a group of sticks may need to be unbundled (decomposed). For example, if you had to take 5 sticks from 23 sticks there are not enough single sticks to do this.

Tens

Š P. Swan

Ones

11

Base Ten Blocks

Make My Number Three-digit numbers Dice and spinners may be used to generate three-digit numbers.

Three ten-faced dice may be rolled and the students asked to create the largest number and the smallest number. Each may be represented on the Place Value Mat. For example, if 4, 2 and 7 are rolled then the students would make 742 and 247. Each number should be depicted on the Place Value Mat. Students will learn that the position of a digit makes a difference, this is a fundamental characteristic of place value.

Place Value Spinners may be spun to generate three-digit numbers.

Hundreds

Tens

Ones

The students can then show the number on a Place Value Mat. Hundreds

Tens

Ones

Specific Place Value Dice may be used to generate three and, later, four-digit numbers.The large block is used to represent 1000, that is, 10 hundreds.

Š P. Swan

19

Base Ten Blocks