writing and evaluating expressions

Writing and Evaluating Expressions

5.OA.15.OA.2

Activator 1Miss Caponigro had some students in her class. Some more students came halfway through the year, then some left before the end. How can you find the total number of students in her class at the end of the school year?

Activator 2Joe had some marbles, but gave some to Billy. Stacey has 2 times as many marbles as Joe has left. How can you find how many marbles Stacey has?

Activator 3Brad had some crackers to go with his soup. He ate some of them. Then he evenly shared the remaining crackers with his friend, John. How could you represent the number of crackers Brad has now?

Learn Zillion Introduction Video

Problem 1:Write a numerical expression to represent:

Double 5 then add 26

(2 x 5) + 26

Problem 2: Write a numerical expression to represent

3 times the difference between 29 and 18

3x(29-18) or 3(29-18)

Problem 3Write a numerical expression to represent

12 more than the quotient of 81 and 9

12 + (81 9)

Problem 4Write a numerical expression to represent

Twice as much as the sum of 2.5 and 4

2(2.5+4) or 2 x (2.5 x 4)

Problem 5

Write a numerical expression to represent

2 less than the sum of and

() – 2

Problem 6Write a numerical expression to represent

5 less than the product of 7 and 8

(7 x 8) -5

Problem 7

Write a numerical expression to represent

Half the difference between

() 2

Problem 8Write a numerical expression to represent

26 less the quotient of 22 and 11

26 – (22 ÷ 11)

Problem 9Write a numerical expression to represent

15 minus the sum of 6 plus 7

15 – (6 + 7)

Problem 10Harper wrote the expression 15n to represent “ the quotient of 15 and n”.

Discuss with your partner why Harper is incorrect.Fix Harpers answer.

Summarizer: Reteach and Practice 6-1

Early Finisher

Day 2: Evaluating Expressions

Activator

Problem 11Write a numerical expression to represent

2 times the difference of 8 and 1

Then evaluate the expression

2(8 – 1)= 14

Problem 12

Describe one way you could read the expression:

0.5 x (24 + 8)

Half of the sum of 24 and 8

Problem 13Maria and her friend go to a movie. At a snack stand they each get a drink for $5 and popcorn for $8. Maria pays for her friend. Write an expression for the cost of a drink and popcorn for two people. Then evaluate the expression.

(5 + 8) x 2 or (5 x 2) + (8 x 2)Maria pays $26

Problem 14Sarah buys a shirt for $12 and pants for $26. They are on sale, so she only needs to pay half of the cost. Write an expression to find Sarah’s cost. Then evaluate the expression

x (12 + 26)Sarah’s cost is $9

Problem 15Write numerical expressions for “the product of 3 and 2, plus 5” and “3 times the sum of 2

and 5”.

Which expression has a greater value?

(3 x 2) + 5 = 113 x (2 + 5) = 21

Problem 16Carol sells bracelets and earrings at a craft fair. Each item sells for $8. Write and evaluate an expression to show how much money Carol makes if she sells 23 bracelets and 17 earrings.

(23 + 17) x 8 = $320

Problem 17Kris ran 3 miles each day for 7 days in a row. One day, she ran an extra mile. Write an expression to represent the total number of miles Kris ran altogether.

3 x 7 +

Problem 18Jan purchased 8 pencils for school. She later decided she needed 7 more. She has made the same purchase before school for the last 6 days. Show how many pencils she has purchased with a numeric expression.

(8 + 7) x 6

Problem 20Mara bought 6 bags of skittles at $0.85 each and 9 packs of gum at $1.20 each for a sleepover. Express what she purchased mathematically.

(6 x 0.85) + (9 x 1.20)

Problem 20 extendedYesterday, Mara bought 6 bags of skittles at $0.85 each and 9 packs of gum at $1.20 each for a sleepover. She still didn’t think she had enough snacks so she went back to the store and purchased the same number of items again. Expressed what she purchased mathematically.

2 x [(6 x 0.85) + (9 x 1.20)] 2 [(6 x 0.85) + (9 x 1.20)]

Problem 21How does the quotient of 200 ÷ 2 compare to the quotient of 200 ÷ 4? Compare the quotients without dividing the numbers. Use a drawing to help.

Since 2 is half of 4 I know the quotient of will be half of the quotient .

Problem 22How does the product of 30 x 3 compare to the product of 15 x 3? Compare the products without multiplying the numbers. Use a drawing to help.

The product of 30 x 3 is double the product of 15 x 3 because 30 is two times greater than 15.

Problem 23How does the product of 3 x (4,564 + 354) compare to the sum of 4,564 + 354?

The product is 3 times greater than the sum of 4,564 + 354.

Problem 22Write an expression that records the calculations below. Do not evaluate your expression

Add 2 and 4 and multiply the result by 3. Add 5 to that product, then double the result.