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4
Balancing Animals
Overview
Shown two pan balances with toy animals, students identify how many of one type of
toy animal will balance another type of toy animal.
Algebra
Understand that substituting one set of animals with a second set of equal weight
preserves balance • Explore equality through the use of pan balances
Problem-Solving Strategies
Reason about proportional relationships
Related Math Skills
Compute with whole numbers
Math Language
Balance • Weigh the same
Introducing the Problem Set
Make photocopies of “Solve the Problem: Balancing Animals” (page 55) and distribute
to students. Have students work in pairs, encouraging them to discuss strategies they
might use to solve the problem. You may want to walk around and listen in on some of
their discussions. After a few minutes, display the problem on the board (or on the
overhead if you made a transparency) and use the following questions to guide a
whole-class discussion on how to solve the problem:
- Look at the pan balances. What do you see? (Two pan balances that show equal weights.
The first pan balance shows that 2 fish balance one frog. The second pan balance shows that 3
frogs balance one shark.)
- Which weighs more—one frog or one fish? (One frog)How do you know? (It takes 2
fish to balance one frog, so the frog weighs twice as much as one fish, or one fish is half the
weight of one frog.)
Algebra Readiness Made Easy: Grade 4 © Greenes, Findell & Cavanagh, Scholastic Teaching Resources 53