7.9.D

Math7th Grade

The Standard

solve problems involving the lateral and total surface area of a rectangular prism, rectangular pyramid, triangular prism, and triangular pyramid by determining the area of the shape's net

Texas Essential Knowledge and Skills for Mathematics

Teacher's field guide

What This Standard Means

What Students Need to Do

Students break a prism or pyramid net into rectangles and triangles, then find each face's area. They add the correct faces to find lateral or total surface area and report square units.

What Mastery Looks Like

Students label every face on a net and calculate each area with the correct dimensions. They add only lateral faces for lateral area and all faces for total surface area, with square units.

Common Misconceptions

Students may include the bases when finding lateral area or leave them out when finding total area. They may use slant height as a base edge, overlook a face, or count a shared edge as a face.

How to Assess It

Give a triangular prism net with triangles of base 6 cm and height 4 cm, plus rectangles measuring 5 by 8, 5 by 8, and 6 by 8. Ask students to label each face, then find the lateral area and total surface area.

Lesson moves

Ways to Teach It

  1. Cut and fold cardstock nets, color the bases blue and lateral faces yellow, then calculate each colored region's area.

  2. Show two different nets for the same solid and ask, "Why must their total surface areas be equal?"

  3. Play a card match game pairing solid diagrams, labeled nets, face-area calculations, and correct lateral and total areas.

  4. Give dimensions for a cereal box or tent and ask students to calculate the material needed with and without the base.

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