A cylinder holds base times height, πr²h. A cone with the same base and height holds one third of that, shown by pouring. A sphere holds 4/3 πr³. The diagonal of a square tile is √2 times its side, and √2 is not a fraction: it is irrational, between 1.4 and 1.5, with a decimal that never ends or repeats. Every rational number has a decimal that ends or repeats, and a repeating decimal turns back into a fraction. The crew finishes the model clubhouse and runs Build Day.