A US schoolteacher who introduced pedal power into her classroom to get her pupils to focus more has said it has led to a significant increase in their performance. Bethany Lambeth who teaches maths at Martin Middle School, North Carolina, said the children were not able to stop moving about during lessons. So she put bike pedals under their desks as a way to divert their energy and found their grades improved too. "Because they're sitting still all day long they start to get restless and start tapping their desks and their feet are moving about," she said. "They're not doing it to be defiant - it's just about being able to move."