Variables are introduced using the example of a squirrel who wants to know where his nuts are buried, and how many he has. A variable is described as a special box that computers keep useful information in. There are two variables in the example - where the nuts are, and how many he has. When one variable is changed, the other automatically changes too.
Children could use a spreadsheet to understand the concept of variables. The variables could be number of days until a birthday, or how many weeks it will take to save for a new toy. In the birthday example, the variables that will change will be today's date and the birthday date. In the example with the new toy, the variables will be the amount of pocket money saved, and the cost of the new toy.