Strong Shapes
Word of the day: triangle
“Builders have a favorite shape that makes bridges and towers super strong. Let's find out which one.”
Grab
- straws or pipe cleaners
- play-dough, mini marshmallows or tape for corners
- a toy to test with
Do
- Build a square from four straws with play-dough corners. Push gently on one corner. It squishes flat.
- Build a triangle from three straws. Push it the same way. It holds.
- Add one straw across the square, corner to corner. Now it's two triangles. Push again.
- Go find triangles: a ladder brace, a bike frame, a crane on a picture, the roof of the house.
The big moment
The square squishes flat. Add one straw across it and it holds.
Ask (guess first, then try)
- Which shape squished?
- How did we fix the square?
What's going on (for you)
A triangle can't change shape without one of its sides changing length, so it stays rigid. A square can lean over into a diamond with all its sides the same. That's why bridges, roofs and cranes are full of triangles.
If they want more
Build the tallest tower you can. Towers with triangles in them stand up better.