Math is a science of dealing with the logic of quantity, shape, and arrangement. It started way back in history. The earliest use of math was in trading, land measurement, painting, and weaving patterns. Math actually coordinates all of the basic learning skills of many subjects such as comprehension, application, and technicalities.
Teaching the subject to an older child may be a bit more difficult. There are many math problems out there that can be used to bring it down to their level. Using this subject in an everyday situation is a one idea. For example, tell a story that involves that child. If he goes to the store and buys a gallon of milk with a five dollar bill and the milk is only three dollars, how much money will he have left? Using word problems will help the child understand it more.