Arch

An arch is like a big rainbow made out of heavy brick or stone blocks. It is used to support heavy things like buildings and bridges. It works by spreading the weight of the heavy things out evenly so that the arch does not break under the weight. It is so strong that it can hold up many tons of weight without collapsing like a normal flat surface would. Imagine building a tall tower out of blocks and then placing a big rainbow on top of it to support the weight - that's what an arch does!