2. Expressions & 3D Geometry

Lesson

- To experiment with how to find the surface area of a composite solid.
- To practice with the surface area of smaller shapes.

- Printed out nets.
- Tape
- Scissors
- Crayons (optional)

- Print and cut out the nets below.
- You can color in the nets using crayons or markers.
- For each of the different shapes in the net calculate the area and record it. Pay attention to the units you used for this.
- Now, fold the nets along the lines to create the shape.
- Tape the edges to secure the shape.

- On your own or in small groups look at each of the solids and make observations. What do you notice about each shape? Come up with at least 3 observations for each solid.
- Draw a sketch of the cross section of each solid.
- How many faces does each solid have?
- What is the surface area of each solid? What units is it in?
- Now use two or more of the nets to make a composite solid. What is its surface area? How did you arrive at your answer? Do this three different times making a new composite solid each time.
- What real-life situations can you think of where calculating surface area of an object could be useful? Brainstorm at least 3 different situations.
- Compare with a friend! Did they think of one you didn’t?

Represent three-dimensional figures using nets made up of rectangles and triangles, and use the nets to find the surface area of these figures. Apply these techniques in the context of solving real-world and mathematical problems.