Lesson 27 introduces communicative law. Then it says to use worksheet 10-2 without an abacus. I'm having trouble figuring out what the worksheet has to do with the communicative law. Worksheet 10-1 (listed as only for extra help) seems to demonstrate it well.
Thanks.

Hello Michelle,

Worksheet 10-2 asks the child to find the sums by applying the commutative law. For example, in 1 5, it is much easier to think of 5 1 than 1 5. That's using the commutative law.

Joan A. Cotter, Ph.D.
RightStart Mathematics by Activities for Learning, Inc.
http://www.alabacus.com

Thank you very much. That makes sense.