Unfold the Box: Surface Area Using Nets

Student Task

• Start by cutting open a small cardboard box along its edges and laying it flat. Ask: "How much cardboard was used to make this box?"
• Teach faces, nets, the area of each face and the surface area formula, then do activities 1 and 2 together.
• Students complete activities 3 to 6. Answers are in the answer key.

Classroom Use

• Box unfold: groups cut open cereal or tea boxes, measure each face and calculate the surface area.
• Cube net hunt: students draw as many different nets of a cube as they can on grid paper (there are 11) and test them by folding.
• Gift wrap challenge: give each group a box and a sheet of paper; they calculate the minimum paper needed before wrapping.

Differentiation

Support: give printed nets on grid paper so students can count squares, and focus on cubes before rectangular prisms. Challenge: find the surface area of triangular prisms and of an open box with no lid, and explain how doubling every side changes the surface area.

Answer Key & Assessment

Activities 1 to 5 check faces, nets and calculating surface area (answer key included). Activity 6 checks applying surface area to real problems and explaining the difference between surface area and volume.

Learning Objectives

• Explain surface area as the total area of all faces of a solid, measured in square units.
• Recognize and use nets of cubes, rectangular prisms and triangular prisms.
• Find the surface area of prisms by adding the areas of the faces and solve real-world problems.

Teacher Tips

Color-code matching faces on the net: top and bottom in one color, front and back in another, left and right in a third. Students then see that a rectangular prism always has three pairs of identical faces, which makes the formula 2(lw + lh + wh) easy to remember.

What's Included

• 7-page printable PDF lesson pack: teacher lesson plan with timings, materials and differentiation
• Key vocabulary list (6 words with meanings and examples)
• Student worksheet (6 activities)
• Editable Word version of the worksheet
• Complete answer key (also as a separate PDF)

Additional Files

• Editable Worksheet (DOCX)
• Answer Key (PDF)

Teacher Reviews