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Home School Life Journal
"Let us strive to make each moment beautiful."
Saint Francis DeSales
painting by Katie Bergenholtz

Building, Part 2: Creating Shapes and Toothpick Trusses

2-D to 3-D
Predicting what 3-dimensional shape might be formed when a 2-dimensional pattern was cut out and folded along dotted lines.

Exploring faces and vertices.They discovered that both the tetrahedron and the pyramid have four triangular faces but that the pyramid also has a square base as its fifth face.

Making structures out of toothpicks and gumdrops.

Which shape is more stable, a triangle or a square?
We learned that triangles made structures more stable because they formed a truss, which is a skeleton-like structure composed of struts, some of which are in compression and some in tension, which are joined to form a series of triangles.
First we built all the same shapes that we had just made with paper using gumdrops and toothpicks this time.
Then we began building a bridge with trusses by constructed a rectangular box of toothpicks and gumdrops. We tested its stability by pressing down on it and wiggling it and found it not so stable.
Next I challenged them to add more materials to strengthen the box. They added cross-pieces and triangular braces. They then extended their trusses to see how wide a gap they could make that still could be stable.

We looked at pictures of bridges which had trusses, which connected what they were learning to real-life situations. After the lesson, I let them go whichever way they wanted to with the materials and they had a wonderful time being creative and their structures just kept on growing!
Activities and photos from 6/23/08.


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3 comments:

  1. Look at how little your guys are! My kids love to play with tooth picks and marshmallows. I need to get that back out and work on some geometry again.

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  2. Yes, it was four years ago, so Quentin was four, James was eight, Sam was eleven, Alex was fourteen and Katie was seventeen. Since they are all about 3-4 years apart, you can basically just shift them over one; I mean James was Quentin's age now, and Sam was James age now, etc. We were reviewing this material this week as we are studying Inventors and Innovators of the late 1800's-early 1900's and we got to suspension bridges. I let them look at the blog posts to refresh their memories as we discussed the concepts. Then it occurred to me that maybe some other people might like to do some of these activities with their own kids, so I thought I would re-post about them.

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  3. Wonderful activities! I love the idea of gummy candies and toothpicks! We can also use the idea of creating constellations as well, just in time for our Space unit. Thank you!

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