We have been finding out about bridges. Bridges have been built for thousands of years all over the world. Bridges can be found in all sorts of places and are used in many ways. We found out that there are many different types of bridges. Designers and engineers need to design and build bridges to suit the purpose they are being used for. Not all designs will work. It depends on what they are needed for.
We decided to make some simple bridges from paper. We tested these and discovered that how the paper is used affects the strength of the bridge.
First we placed a sheet of paper between our bridge piles. We used plastic tops to test with and found that our bridges quickly sagged.
For our second test we folded the sides of the paper up and repeated our strength testing. Our bridges were much stronger. We could pile on a lot more tops.
When we placed a cardboard arch underneath our bridges they could support even more plastic tops.
Finally we used a second piece of paper and pleated it. Wow! The strength of our bridges when we placed this underneath the top layer of paper was enormous.
The triangular shape created by the pleating made an enormous difference to the strength of our bridges. Triangles and arches continue to be used for bridge strength. You can see them when you look at bridge images.
It was fun making and testing our bridges. We had to work together, persist and use our problem solving skills.