Write "associative property" on the whiteboard. Ask the students if they know the words on the board or any part of the word. Students will be able to explain property in math terms by saying it's a rule. The students know the word associate. Underline that part of the word and discuss with the students what it means to associate with someone. Lead them to define the word as connecting with someone or something.
Ask three friends to the front of the class to demonstrate the associative property. Place the first two friends within the large cut-out parenthesis, and the third friend is outside the parenthesis. Explain to the class that sometimes you plan an event with one friend. Move the parenthesis to the last two friends and explain that sometimes you plan an event with another friend. You are all associates. It doesn't change your friendships, or associations. The grouping is changed; however, you are still friends.
Give each student linking cubes in four different colors. Present an addition problem which expresses the associative property -- (3 + 5) + 7 = 3 + ( 5 + 7). Designate a color of cube for each of the addends and for the sum. Place the colored three cubes and the colored five cubes together. Add on the seven cubes to represent the last addend. Make a cube of a differing color that is the same length of the total cubes to represent the sum. Fifteen is the sum in this case. Next, link together cubes in the right color and amount for five and seven. Lay out this part of the equation first. The order of operations in math dictates the parenthesis are done first. Place the cubes that represent three in front of the string of cubes. Move the sum, string of 15, underneath this string of cubes.
Discuss with the students their discoveries by doing the hands-on activity with the linking cubes to illustrate the associative property of addition. To further support their learning and memorization of the property, provide a teacher-generated worksheet with (a + b) + c = a + ( b + c) displayed at the top. Provide one side of the equation and ask the students to complete the other side. Understanding is evident at this point. The students who don't understand will be trying to solve the equation. The students who understand and have memorized the property will fill in the blanks based on their knowledge of the property.