We have been investigating how bridges are so strong.
We used polydron to experiment with the idea of triangulation – triangles are the strongest shape because the force can be shared by the 3 sides rather than being heavy down one side.
We had to build a bridge that could withstand 200g for 30 seconds using only triangular polydron pieces. After testing, we talked about why some designs were stronger than others- they had triangles orientated downwards!
We then learned about beam bridges- a simple engineering design using a plank across a gap. We learned how this can not be too rigid if the gap is long, or the load is too heavy. We investigated reinforcing the beam bridge using piers. We found that without a pier the bridge couldn’t hold 20g of weight, but with piers it could take 900g. We then used triangulation to reinforce our piers to make them even stronger- some held over 1kg on a paper beam bridge!
Within the lesson we used cuboid nets to create our piers.