Properties of Addition Lesson 1-4

Three Properties of Addition 1.Commutative 2.Associative 3.Identity

The Commutative Property Background –The word commutative comes from the verb to commute. –Definition on dictionary.comdictionary.com Commuting means changing, replacing, or exchanging –People who travel back and forth to work are called commuters. Traffic Reports given during rush hours are also called commuter reports.

Here are two families of commuters. Commuter A Commuter B Commuter A Commuter B Commuter A & Commuter B changed lanes. Remember… commute means to change.

Here is another example…

Think of this hypothetical situation: Every day you ride your bike to school. The distance from home to school is 2 miles. The distance from school to home is also 2 miles. How do we know this? Think of this hypothetical situation: Every day you ride your bike to school. The distance from home to school is 2 miles. The distance from school to home is also 2 miles. How do we know this? Did you notice that hypothetical and hypothesis look almost the same? Hmmmm... Think about what hypothesis means…

HomeSchool The distance from Home to School is the same as the distance from school to home. Home + School = School + Home H + S = S + H A + B = B + A

The Commutative Property A + B = B + A

Three Properties of Addition 1.Commutative 2.Associative 3.Identity

The Associative Property Background –The word associative comes from the verb to associate. –Definition on dictionary.comdictionary.com Associate means connected, joined, or related –People who work together are called associates. They are joined together by business, and they do talk to one another.

Lets look at another hypothetical situation Three people work together. Associate B needs to call Associates A and C to share some news. Does it matter who he calls first?

ACB Here are three associates. B calls A firstHe calls C last If he called C first, then called A, would it have made a difference? NO!

(The Role of Parentheses) In math, we use parentheses to show groups. In the order of operations, the numbers and operations in parentheses are done first. (PEMDAS) So….

The Associative Property (A + B) + C = A + (B + C) AC B AC B THEN The parentheses identify which two associates talked first.

Three Properties of Addition 1.Commutative 2.Associative 3.Identity

The Identity Property of Addition I am me! You cannot change My identity!

Zero is the only number you can add to something and see no change.

Identity Property of Addition A + 0 = A + 0 =

Lets practice ! Look at the problem. Identify which property it represents.

(9 + 8) + 7 = 9 + (8 + 7) The Associative Property of Addition It is the only addition property that has parentheses.

= 12 The Identity Property of Addition It is the only addition property that has two addends and one of them is a zero.

9 + 7 = The Commutative Property of Addition It is the only addition property that has numbers that change places.

4 + 6 = The Commutative Property of Addition Numbers change places.

3 + 0 = 3 The Identity Property of Addition See the zero?

(4 + 3) + 2 = 4 + (3 + 2) The Associative Property of Addition It has parentheses!

a + 0 = a The Identity Property of Addition Zero!

a + b = b + a The Commutative Property of Addition Moving numbers!

A (a + b) + c = a + (b + c) The Associative Property of Addition Parentheses! CB