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K–12 teaching and learning · from the UNC School of Education

Area of solids

Finding area of rectangular solids and cylinders by cutting them into flat pieces and adding the areas.

A lesson plan for grades 7–12 Mathematics

By Dorothy Carawan

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Learning outcomes

Students will:

  • learn the concepts of lateral area and total surface area as applied to rectangular solids and cylinders, and how mathematical formulas for surface areas of solids relate to these concepts.
  • discuss application of these concepts and formulas in real life.

Teacher planning

Time required for lesson

1.5 hours

Materials/resources

Twelve pack box of soft drink cans
Measuring device(ruler or tape measure)
Graph paper or plastic graph sheet (can be purchased at WalMart-the size of a placemat)

Technology resources

Calculator

Pre-activities

Formulas for area of a rectangle and circle.

Activities

  1. Students gently tear open the carton surrounding the cans, opening all the seams until the cardboard will lie flat.
  2. 2. Students measure the carton one piece at a time, recording the dimensions of each piece.
  3. Students transfer the measurements to the graph paper and count the units on the graph paper, then find the total area of the solid by using individual area formulas for rectangle, square, circle, etc.
  4. Students use established formulas for surface area and lateral area of solids to find the area of the carton another way.
  5. Students compare the answers obtained by the two different methods.
  6. Students compare answers with each other.
  7. Repeat the same procedure for the soft-drink cylinders (as an alternative, use a cardboard cylindrical container, such as an oatmeal container).
  8. Let the students figure out the amount of cardboard and/or aluminum needed and the approximate cost of producing the containers (you can assume a per-square-foot cost of each material, or have curious students research this on the internet or by contacting soft-drink companies). Discuss how this affects the cost of the drinks.

Assessment

Students must turn in their graphs and worksheets showing the formula problems. Also, one student from their group would make an oral presentation.

Supplemental information

None

Related websites

N/A

Comments

Lessons similar to this are found in the Cord material.

North Carolina Curriculum Alignment

Mathematics (2004)

Grade 7

  • Goal 2: Measurement - The learner will understand and use measurement involving two- and three-dimensional figures.
    • Objective 2.02: Solve problems involving volume and surface area of cylinders, prisms, and composite shapes.

Grade 8

  • Goal 3: Geometry - The learner will understand and use properties and relationships in geometry.