How to Teach the Commutative Property to Second Grade

Commutative property of addition is easier to grasp than the name sounds.

Commutative property in math has two basic rules -- one addition rule and one multiplication rule. Commutative property of addition states that changing the order of the digits being added does not change the sum -- for example, a + b = b + a. The commutative property of multiplication states that changing the order of the digits being multiplied does not change the product -- for example, a x b = b x a. There are no commutative property rules for subtraction or division.

Things You'll Need

• Chalkboard or whiteboard
• Eraser for board
• Writing device for board
• Paper
• Pens or pencils

Instructions

Teaching Commutative Property Addition to Second Graders

1. Erase everything on the black or whiteboard. Give the students paper and writing instruments so they can do the math problems along with you.

2. Write "a + b = b + a" on the board and tell the students that this is the commutative property of addition rule. Explain that it means that if you add two numbers together, the order of the numbers does not matter as they will equal the same number.

3. Supply the students with examples. Ones suitable for their grade level are "1 + 2 = 2 + 1" and "2 + 3 = 3 + 2." Add the figures up to show the children that both sides of the equation have the same total.

Teaching Commutative Property Multiplication to Second Graders

1. Erase everything on the black or whiteboard.

2. Write "a x b = b x a" on the board and tell the kids that this is the commutative property of multiplication rule. Explain that it means that if you multiply two numbers together, the order of the numbers does not matter as they will equal the same number.

3. Supply the students with examples. Ones suitable for their grade level are "1 x 2 = 2 x 1" and "2 x 3 = 3 x 2." Add the figures up to show the children that both sides of the equation have the same total.

Tips & Warnings

• Once the students have grasped the commutative property rule, give them examples of problems that are not commutative property. One easy to grasp example for second graders is a + b - 1 = a + b.

• Commutative property also applies to some problems that combine addition and multiplication. For example, (a + b) × (y + z) = (y + z) × (a + b).

• The word “commute” means “exchange” or “swap over” hence calling this math principle the commutative property rule.

References

• Basic Math and Pre-Algebra; Research and Education Association
• Elementary Algebra; Charles P. McKeague