Objective: To use the correct order of operations when simplifying real number expressions.
Materials: none
Grouping: Whole class, individuals
1. Give the following example to the students:
Leah has $25.00 Tomorrow she has to give 3 friends back $6.00 that she owes each of them. How much money will she have left after she pays back her friends?
The problem is then: 25 - 3 x 6 = ?
If you go from left to right: 25 - 3 x 6 = 22 x 6 = 132.
This answer doesn't make sense. How could she have more money than when she started, if she had to give away some money to repay her debts?
So, there is a different order to work the problem:
25 - 3 x 6 = 25 - 18 = 7.
She has $7.00 left after she pays back her friends.
2. This should show that there is an appropriate order to go in when working a problem.
3. Display the order of operations on the overhead (provided below). Go through this order thoroughly before allowing students to go out on their own. (Use the phrase "Please Excuse My Dear Aunt Sally" as a memory device to help students to remember the correct order). You may give each student a copy for their notebooks.
4. Give students more examples, which are provided. Be sure to go through the list of order of operations each time to get students into the habit of doing this each time.
5. Assignment: Give individual students the worksheet for homework.
Perform operations in the following order when simplifying an expression:
II. Exponents
III. Multiplication & Division---from Left to Right
IV. Addition & Subtraction---from Left to Right
PEMDAS********"PLEASE EXCUSE MY DEAR AUNT SALLY'
More examples on Order of Operations:
3. (3 + 2) - (4 + 1) = ______ 4. 10 x (5 - 2) + 1 = ______
5. 8 - 4 + 3 x 2 = _________ 6. 45 / (11 - 2) x 6 = ______
7. 12 x (5 - 3) - 10 = ______ 8. 7 x 3 + 23 = ___________
9. 3^2 + 6 / -5 = __________ 10. 4^2 - (5 + 7) / -2 = _____
Order of Operations:
Worksheet
1. 15 x 2 + 1 = _________ 2. 5 + 3 x 2 = __________
3. 30 - (6 + 5) = _______ 4. 24 / (5 + 3) - 7 x 0 = _____
5. (6 x 4) / (8 - 5) = ______ 6. 5^2 - (6 - 2) / 7 = ______
7. (12 + 8) / -4 = ______ 8. (3^3 + -12) + 3 x 2 = _______