standard_description: Prove theorems about triangles. Theorems include: a line parallel to one side of a triangle divides the other two proportionally, and conversely; the Pythagorean Theorem proved using triangle similarity.
problem_activity: Narrative
The purpose of this activity is for students to build and compare flat and solid shapes. Students are not expected to build precise shapes. Using clay to build the shapes helps students feel the difference between flat and solid shapes. The terms “flat” and “solid” are introduced in the activity synthesis. Students may benefit from getting to hold and see the solid shapes up close as they build them.
Required Materials
Materials to Gather
Clay
Required Preparation
Each student needs a piece of clay.
Gather a cone and cylinder to display.
Launch
Groups of 2
Give each student a piece of clay.
“Use your clay to make a shape that you know.”
1 minute: independent work time
“Share your shape with your partner. How are they the same? How are they different?” (The shapes are different. I made a circle and my partner made a triangle.)
30 seconds: quiet think time
1 minute: partner discussion
Share responses.
Activity
Display a cylinder.
“Make this shape with your clay.”
2 minutes: independent work time
Display a cone.
“Make this shape with your clay.”
2 minutes: independent work time
“Describe the shape that you made to your partner. What does it look like?” (It looks like an ice cream cone. It’s tall. It has a point on the bottom.)
30 seconds: quiet think time
2 minutes: partner discussion
Share responses.
Student Response
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Activity Synthesis
Display a group of flat shapes and a group of solid shapes that students created.
“What is different about the shapes that we made first and the rest of the shapes that we made?” (The shapes that we made first are all flat. The other shapes stick up.)
“The first shapes that we made were flat shapes, like circles and rectangles. Then we built some other shapes. What can we call these shapes?” (solid shapes, big shapes)
“These shapes are solid shapes.”
“Use your clay to make a flat shape.”
“Use your clay to make a solid shape.”


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