Lesson Summary
In this learning experience the students review some examples of tension and compression in the classroom and in their homes. Then they explore tension and compression in different structural shapes including triangles, squares and their own structures. They will learn about a structural framework called a triangular truss. They will learn how triangular trusses use tension, compression and the triangular shape for strength.
Teacher Background
The students will use tension and compression for strength. They will learn that trusses are triangular frameworks that use tension and compression for strength. They will demonstrate tension and compression in a triangle.
Set-up/Management Tips
- Construct a triangle using three straws connected with paper clips. Prepare the tension and compression triangle demonstration outlined on teacher’s manual pages 172 and 173.
- Prepare the following materials: 4’ string, 30 paper clips, 15 straws, 10 washers, 1 pair of scissors for each group) ahead of time. This allows the students to use the class time for building instead of counting materials.
- Collect photos of structural frameworks that show triangles that are supporting loads. Examples might include billboards, awnings, bridges, fences and gym ceilings.
- Make copies of the following pages 183, 185, 187, 189: Group Recording Sheet A-Tension and Compression: Triangles, Group Recording Sheet A-Tension and Compression: Triangles page 2, Group Recording Sheet B-Tension and Compression: Triangles, Group Recording Sheet B-Tension and Compression: Triangles page 2,
- Optional Home-School Worksheet Tension and Compression: Triangles page 191 of the teacher’s manual.
- Science notebook questions and writing suggestions for this learning experience are listed below:
As the students are building and comparing tension and compression in triangles and squares have the students take notes as outlined on page 177 of the teacher’s manual.
After the students have shared their squares and triangles have the students respond to the questions listed on page 178 of the teacher’s manual.
Have the students read and summarize an article about triangular trusses from a book or website. The following web article was recommended http://www.swan.ac.uk/civeng/teaching-ug/stiffness/trusses/trusses.htm. This is outlined on page 179 of the teacher’s manual.
After the students have identified the areas of tension, compression, and triangular trusses in their improved structures, and reported the increased load these structures were able to hold have them respond to the following questions listed on page 180 of the teacher’s manual.
Literacy Support
Scientific Vocabulary
The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit:
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