Students will need the Geometric Solids Tool for this lesson.
As students are exploring the various geometric solids, begin a class discussion which includes the following points.
Students should note the following characteristics:
- Each solid has flat sides called faces.
- Each solid has edges to connect the faces.
- Each solid has corners that connect the edges. (Note that the activity sheet refers to corners as "vertices", so you may wish to familiarize students with this vocabulary.)
If you have these shapes in your classroom, have students find the shapes that match those in this computer activity.
This lesson is designed to help students focus on the properties
of each shape. The tools allow them to color the faces, edges, or
corners (vertices) easily by holding the shift key while clicking the
mouse on the paint palette and then on a face. (The edges are always
white and the corners black.)
Distribute the Exploring Geometric Solids activity sheet to the students.
Teacher Note: For today's lesson, students will only
complete the table on the activity sheet. Save the three questions
below the table for tomorrow's lesson.
As students complete the activity sheet, guide them as needed.
For example, when asking "How many sides does each face have?", guide
the student to click the given face, and color the sides. When
determining the number of faces, it may be helpful to color the faces
and count as they color. (It's interesting to observe students doing
this: some color all faces the same color, while others color the faces
After determining the number of faces, students are asked to
count the number of edges and vertices (corners) in the solid. Before
actually counting the number of edges, students may wish to "guess" the
For example, working with the dodecahedron, a student may say
each face has five sides — a pentagon. She counts 12 faces. In guessing
the number of edges, she may estimate 60 and give as her reason,
"5 sides × 12 faces = 60 edges." Counting the edges with the result
of 30 provided an opportunity to have her take a second look at the
dodecahedron and find out why. (Each edge is shared by two faces.)
Taking advantage of opportunities such as these enriches student understanding.