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how do i solve associative property problems for second grade

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Dec 11, 2010
Associative Property
by: Staff

The question:


how do i solve associative property problems for second grade


The answer:


During second grade, commutative and associative laws are applied (ONLY) to ADDITION and SUBTRACTION problems.

(In third grade, the commutative and associative laws will be applied to multiplication.)

Students are taught to use the commutative and associative laws for three reasons:

1. to show them how to simplify mental calculations
2. to show them how to check their answers when they complete arithmetic problems.
3. prepare them for algebra

You only asked about the associative law, but both laws are similar.

The COMMUNICATIVE law: you can add or subtract numbers in any order:

Addition:

2 + 7 = 7 + 2

In both cases, the answer is the same: 2 + 7 = 7 + 2 = 9


Subtraction:

8 - 3 = -3 + 8

In both cases, the answer is the same: 8 - 3 = -3 + 8 = 5


The ASSOCIATIVE law: any series of numbers can be grouped in any way and added any order without changing the final result.

Addition:

2 + 7 + 1 = (2 + 7) + 1 = 2 + (7 + 1)

It does not matter whether you begin by adding the 2 and the 7, or begin by adding the 7 and the 1.

Either way, the answer is the same: 2 + 7 + 1 = (2 + 7) + 1 = 2 + (7 + 1) = 10


(Negative Numbers) Subtraction:

8 - 3 + 1= (8 – 3) + 1 = 8 + (– 3 + 1)

Either way, the answer is the same: 8 - 3 + 1= (8 – 3) + 1 = 8 + (– 3 + 1) = 6



HOW TO UNDERSTAND & PRACTICE THESE CONCEPTS

During second grade, using pictures, blocks, or other types of manipulatives will help make these concepts workable and fun for students.

For example, take the following problem:

1 + 2 = ?

Place a large dot (star, square, smiley face, etc.) on a piece of paper to represent the number 1.

Place two large dots on the same piece of paper in a different color to represent the number 2.

A student can now count the dots, either beginning with the 2, or beginning with the 1.

A student can quickly see that it does make any difference whether he or she starts with the 2 or with the 1. In both cases, the student will arrive at the same answer.

You can also use problems such as the one shown below. Have the student fill in the blank:

2 + 3 = ___ + 2


PREPARING FOR ALGEGRA

Understanding the associate law is very important.

DON’T give a second grader a calculator. He or she must understand the concept. Using a calculator to take a shortcut to the answer will only cause problems later.

Once a student understands that:

2 + 5 = 5 + 2

He or she will have less trouble understanding that:

X + Y = Y + X






Thanks for writing.


Staff
www.solving-math-problems.com

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