After the bridges were built we tested them. The bridges were held up by books on each side and nothing in the moddle so it would be like a real bridge. We tested them by putting weights on them and seeing which bridge would with stand the most weight.

Conclusion

After testing all of the bridges we found out the following. The stongest bridge was the suspension bridge, it held 2.5 kilograms. The second strongest bridge was the beam bridge, it held 1.5 kilograms. The weakest bridge was the under support bridge, it held 1.4 kilograms. We thought that the under support bridge would be the strongest but it wasn't the supports under gave out and the bridge broke. The suspension bridge would have held more but the suspension strings weren't distributed equally.