Algebra Readiness Made Easy Grade 4

WEIGH IN

• How can knowing that Tom weighs 85 pounds

help you figure out Smudge’s weight? (If Tom

weighs 85 pounds, and the total weight of Tom and

Smudge is 100 pounds, then Smudge must weigh

100 – 85, or 15 pounds.)

• How can you figure out Alex’s weight? (On scale

C, Tom and Alex weigh a total of 125 pounds. Since

Tom weighs 85 pounds, Alex weighs 125 – 85, or 40

pounds)

Work together as a class to answer the questions

in “Solve the Problem: Weigh In.”

Math Chat With the Transparency

Display the “Make the Case: Weigh In” trans-

parency on the overhead. Before students can

decide which character is “sharp as a tack,” they

need to figure out the answer to the problem.

Encourage students to work in pairs to solve the

problem. Then bring the class together for

another whole-class discussion. Ask:

• Who has the right answer? (Ralph Rhino)


• How did you figure it out? (On scale C, five bags

of rocks weighed 10 pounds. So one bag of rocks is

10 ÷ 5, or 2 pounds. Since a bag of rocks is 2

pounds, the fishbowl on scale B is 7 – 2, or 5

pounds. Since a fishbowl weighs 5 pounds, James on

scale A must weigh 75 – 5, or 70 pounds.)

• How do you think Wally Walrus got the answer

of 68 pounds? (He probably subtracted the weights

of both the bag of rocks and the fishbowl, or 7 pounds,

from 75 pounds.)

• How do you think Marlee Marlin got the

answer of 73? (She probably subtracted the weight of

the bag of rocks from 75 pounds instead of subtract-

ing the weight of one fishbowl.)

43

WEIGH IN

44

I know how much Tom

weighs. I’ll write that

number on all his pictures.

11 ..What number of pounds will Ima write

on Tom’s pictures? __

22 ..Alex the dog weighs __ pounds.

33 ..Smudge the cat weighs __ pounds.

44 ..How did you figure out the number of pounds for Smudge?

---

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SSOOLLVVEE

TTHHEE

PPRROOBBLLEEMM

Ima Thinker

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Name _____ Date __

How much does each one weigh?

Scale A Scale B Scale C

WEIGH IN

Name _____ Date __

MAKE

THE

CASE How much does James weigh?

45

Wally Walrus Ralph Rhino

Marlee Marlin

No way!

James weighs

70 pounds.

That’s easy.

James is 73

pounds.

It’s clear.

James weighs

68 pounds.

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Who is sharp as a tack?

Note:

The bags of

rocks weigh the

same amount.

Scale A

Scale B

Scale C

Algebra Readiness Made Easy: Grade 4 © Greenes, Findell & Cavanagh, Scholastic Teaching Resources