This is a Level 2 Geometry activity from the Figure It Out Series.
A PDF of the student activity is included.
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identify two dimensional faces on three dimensional shapes
FIO, Level 2-3, Geometry, Post It!, page 2
Play dough or clay
Activity One
Posting boxes encourage young children to look at the shape of the faces and cross-sections of threedimensional solids. The dimensions of the posting holes are usually worked out so that a block may pass through only one hole. (The posting holes for this question are a circle, a rectangle, a square, and a triangle.) In this case, each shape that has a cross-section or face that is the same as a given solid will be able to post through that solid’s posting hole.
For example, the cylinder has a rectanglar cross-section when sliced vertically and a circular cross-section when sliced horizontally. The cylinder will post through the circular and rectangular holes.
Similarly, the pyramid will fit through the triangular and square holes.
Activity Two
For this activity, students will need to visualise solids that have the cross-section shapes shown in the problems.
The octagonal prism will have an octagonal and a rectangular cross-section.
The triangular prism has a triangular and rectangular cross-section.
Answers to Activity
Activity One
1. cylinder
2. pyramid
3. cube: the square hole and the circle (if the circle is big enough)
cone: the triangle hole and the circle hole
Activity Two
Answers will vary.