The pupils of St Lawrence college had fun making a radio that powers itself, with no need for a battery, as part of National Science week. The Hilderstone Radio club, assisted by the Ramsgate Vikings model boat club, explained the basics of radio and how the signal is carried by the radio wave using amplitude modulation or AM. In their physics lesson, the pupils constructed the radio, commonly known as a crystal radio. They were delighted when they found they could pick up a signal in their earphones. Steve Cockshoot and Terry Alexander then shown them the principles of using a crystal and a radio signal to control the engine and rudder of a model boat. Teacher Mrs Kouthouri said the pupils appreciated seeing their physics knowledge and lessons being used in real applications.