Sign in to view assessments and invite other educators
Sign in using your existing Kendall Hunt account. If you don’t have one, create an educator account.
Arrange students in groups of 2. Give students 30 seconds of quiet think time to look at the nets, followed by 2 minutes to describe, with a partner, each net.
Here are some nets for various prisms.
What would each net look like when folded?
The goal of this discussion is to identify the prisms from their nets and to share key features of nets of prisms. Ask selected students to describe the object formed by each net. Record and display their responses for all to see. If a student's description does not include the name of the prism, ask other students to name the object and to explain how they know.
Ask students to share what they notice about all of the nets. Record and display their responses for all to see. While students may notice many things, important ideas to highlight during the discussion are:
To Copy (from Blackline Masters)
Making the Prism Handout
In this activity, students take the triangle they selected in the previous activity and use it as the base of their triangular prism.
Demonstrate the positions at which triangles should attach to the rectangle to form a net, by displaying an example and describing the important parts:
After students have drawn their net and before they cut it out and assemble it, make sure they have correctly positioned their bases—opposite from each other on the top and bottom of the rectangle and reflected. It will also make assembling the net easier for students if they draw lines subdividing the large rectangle into the individual rectangular faces and draw tabs where the faces will be glued or taped together.
The goal is to make sure that students understand how the changes in the base triangle affect the prism’s surface area and volume. Select students to share their answers for the cross-sections. For cross-sections taken in these two ways, all triangular prisms should have the same shapes as answers, although the actual size of the cross-section will differ based on the size of the base triangle and the height of the prism.
The volume and surface areas will depend on the triangle they have chosen to use as their base.
Select students to share their methods for computing volume and surface area. The base area is important in the calculation of each, so students should use the values they computed in the previous activity.
Optional
MLR8: Discussion Supports
None
Students combine their solid with a partner’s and examine the new solid’s properties.
Arrange students in groups of 2.
As you answer these questions about your new prism, look for ways that you can use your calculations from the previous activity to help you. Explain or show your reasoning.
If students struggle with calculating the area of the base of the new prism, consider asking:
The purpose of this discussion is to explore which attributes of the larger prisms were easiest to determine based on the original prisms and which were hardest.
Using two prisms that are identical, demonstrate putting them together against a matching side in various ways.
For each configuration, discuss with students:
In the first configuration,
In the second and third configurations,
How could you put these two prisms together to make the largest surface area possible for the new prism? The smallest surface area possible?
If time allows, this activity can be extended to review relationships between angles as well.
Help us improve by sharing suggestions or reporting issues.
Your teacher will give you an incomplete net. Follow these instructions to complete the net and assemble the triangular prism:
After you finish assembling your triangular prism, answer these questions. Explain or show your reasoning.
What is the surface area of your prism?
Stand your prism up so it is sitting on its triangular base.