builds on the process of observing. We learn much about the size, shape, color, texture and so on of objects by comparing them to different objects. We separate objects on the basis of similarities and differences. When we do, we develop concepts of higher-order relationships than we do by merely describing observations. To find out more about an unfamiliar object, scientists often match or compare it to something they know well. In fact, all scientific measures using rulers, balances, thermometers, watches, and so on, rely on comparing an unknown object to something that is known: the instrument.