Demonstrating Newton’s laws of motion, this enduring favourite consists of five metal balls hanging from two wires. When you pull the first ball away and let it fall back to hit the others, the ball on the opposite side will move with the same momentum as the first. Watching the perpetual movement and hearing the sound of the balls hitting each other is said to stimulate creativity, concentration and relaxation thanks to its hypnotic quality, so you’ll be tearing through that to-do list in no time. If you can just… tear… your eyes… away…