Education - how does a keyboard work?

There is a matrix (like a criss-cross pattern) of wires in a keyboard which form a circuit. When you press one of the keys, the metal plate under the key touches the matrix and forms a different circuit with a different amount of electrical current flowing through it. The keyboard works out from this which keys are pressed up or down. It converts each key to a code (ASCII, where a space bar is 32 and the letter A is 65) and sends this information to the computer.