It is the kind of experiment which gets kids excited about science. Mixing Mentos sweets with Diet Coke produces a surging fountain of cola – and now it has won two pupils £2,000 of science equipment to boot.Teresa Logan and Stephen Lynch's choreographed display of the cola and mint sweets exploding in a dramatic Christmas tree shape has triumphed over hundreds of other entries in the Mentos science competition. But it was not down to luck (or an understanding of the nucleation process which produces the spectacular effects), according to their teacher, Linzi Wetherell. They conducted many experiments to get the right combinations and timings before the big show at Gunnersbury Catholic School in Brentford, Middlesex, she said. They eventually used 30 bottles of Diet Coke and 120 Mentos, with four of the mints strung together before being dropped into the drink.