Jean-FranƯcois seeks to understand why arches with their arc shape are so strong. How does gravity hold them in place without glue or cement? To find out, we meet a mason from the Middle Ages, we build an ark out of cheese and we sing the praises of flying buttresses. Investigation and pratiko-pratikChanelle and Francis find arches and arches in a playground, above windows and doors as well as on bridges. They meet LeÞila, a pure and applied science student, who shows them how to create the strongest type of arch with rope! Using giant pieces of cheese, each team must build a two-meter high arch that is held in place by gravity. No glue allowed! Then the teams must pass a resistance test to their structure by depositing balloons filled with water. The builders of the strongest arch win not only victory, but also real pieces of cheese! Neuron BrawlMichelle and Teanna chase a surprise shape by attaching colorful rubber bands to studs. They must use their spatial skills to predict what shape will result.