There are thousands of bridges in the UK that are designed in different ways. A basic beam bridge consists of a straight beam supported by two piers, but other designs include arch bridges and suspension bridges.
Encourage students to observe different bridges while they are travelling or by looking in books and magazines. Challenge them to build the strongest bridge they can, using only one A5 piece of construction paper. They can cut and fold the paper, but they can't use glue or sticky tape.
Set up an area where the structures can be tested. This can be done by sticking two small boxes on to a flat piece of card. Make sure the boxes are placed half the length of the A5 paper apart. The bridge needs to span the boxes, but they can also be used as anchor points for an arch bridge.
Test each bridge individually by placing weights on its centre until it collapses. The weights could be coins or wooden counters and must all be of equal weight.
Encourage your students to experiment, testing which design works best.
Common ideas include folding the A5 paper in half lengthways; cutting the paper into strips and placing the strips on top of each other, and making an arch from a length of the paper and placing a separate piece over the top.
Once each team has a design, explore the differences between each of the structures. Which was the worst and which was the best? Test the final designs and see whether the students' predictions are correct. Ask them if glue or sticky tape would have made a difference, and to try new designs making use of these materials. How does this change their approach? Are there similarities between the bridges constructed this way?
Sophie Duncan is project manager for science at the BBC www.bbc.co.ukscience