The oldest beam bridges are called 'clapper bridges'. Piles of stones were placed in a river. Flat stone slabs were laid across them. Many examples of clapper bridges can still be found in some parts of England.

Modern beam bridges are made with hollow girders and frameworks or trusses. In a truss, the struts and ties are held together at the ends with bolts. The triangular shapes formed by the struts and ties keep the whole truss in shape.

Arch Bridges were first built by the Romans more than 2000 years ago. One of their most famous bridges was the 'Pont du Gard' in the South of France. It was made from huge blocks of stone and consisted of 3 levels of arches on top of each other.

The very first bridge to be made of iron was an arch bridge. It was built over 200 years ago across the River Severn in Shropshire. It became so famous that the place where it was built was named 'Ironbridge'.

Some bridges are designed to move and change position. One of the many bridges across the River Thames in London is Tower Bridge. This is a kind of drawbridge. It is over 100 years old and it took 8 years to build. It is made up of two cantilevers that can be raised and lowered. When they are lowered, they meet in the centre and allow cars and pedestrians to cross. If a tall ship needs to pass below the bridge, then the traffic is stopped and the cantilevers are raised.

Instead of raising up and down, some bridges change position by rotating on a pivot. These are known as swing bridges. In their usual position, swing bridges allow traffic to pass over the top. When a boat approaches, the pilot has to stop and get out. He then has to unlock the swing bridge and push it open. Once the boat is safely on the other side of the bridge, the pilot must always remembet to close and lock the bridge again. A local example of a swing bridge can be found crossing the Leeds-Liverpool canal in Netherton.

One of the many traditional tales 4H have heard in their lessons about India is the story of the Monkey Bridge to Lanka. In this story, the animals of the forest to help Rama to rescue his wife by building a bridge across the sea. The children demonstrated traditional Indian dance to tell the story of the Bridge to Lanka.

Click here to learn more about Year 4's Indian Dance Day.