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Stamp Stumpers
Overview
Presented with a set of stamps—some with geometric shapes and others with prices—
and its total cost, students figure out the price of each shape stamp.
Algebra
Solve equations with one variable • Replace symbols with their values •
Recognize that the same pictures have the same value • Understand that taking away
an addend changes the sum by the same amount
Problem-Solving Strategies
Reason deductively
Related Math Skills
Compute with whole numbers • Recognize chevrons, hexagons, octagons, pentagons,
squares, trapezoids, and triangles • Recognize cones, cubes, and cylinders
Math Language
Total cost • Geometric shapes: chevron, hexagon, octagon, pentagon, square,
trapezoid, triangle, cone, cube, cylinder
Introducing the Problem Set
Make photocopies of “Solve the Problem: Stamp Stumpers” (page 22) 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:
- What do you see? (4 chevron stamps, one 5¢ stamp, and a receipt showing a total cost
of 13¢)
20 Algebra Readiness Made Easy: Grade 4 © Greenes, Findell & Cavanagh, Scholastic Teaching Resources