1. Goal: The learner will write variable expressions and equations.
Lesson 12.1

2. Key Phrases These words signal what operation needs to be preformed.
Addition
Subtraction
Multiplication
Division
Plus
Minus
Times
Divided by
The sum of
The difference of
The product of
The quotient of
Total
Decreased by
Multiplied by
Separate into equal parts
Added to
Less than Of
More than
Subtracted from
twice
These words signal what operation needs to be preformed.

3. Write the phrase as a variable expression
3 pieces added to x pieces in the art show
The sum of 4 and a number n
The difference of 12 and a number x
9 fewer than the number of boys b

4. A Few For You 16 decreased by a number d
The total of 10 and a number n
A number h increased by 15

5. Try It Again. The product of 5 and the number of girls, g
8 multiplied by a number, x
The quotient of a number, h, and 6
24 divided by the number of hours, h

6. What if…
Sometimes they don’t give a specific variable to use. Pick a variable that makes sense.
Try not to use O, T, or S
25 divided by the number of inches
Twice the number of people

7. Writing Equations “equals” and “is” represent “=“
A number x minus 5 equals 12.
15 times a number y is 75.

8. You Try It
A number n added to 4 is 11.
The quotient of x and 96 is 8.

9. Model a Situation
Today’s high temperature of 59˚F is 3˚F less than yesterday’s high temperature t. Write a subtraction equation you can use to find t.

10. Model a Situation
Three friends share the cost of a dinner equally. The total cost of the dinner is $27. Write a multiplication equation that you could use to find the amount a that each friend pays.

11. Assignment
P.631 #3-17, 29-32
Challenge 24-25