If you teach Personal Finance, this is a great tool for helping students develop a "pay yourself first" budgeting philosophy. It also can be used to teach the use of spreadsheets and mathematical formulas, as well as math concepts like percentages.
Students start by entering their projected monthly salary. Then they allocate, by percentage, how much will go to various types of investment and savings funds. They finish by entering their expected monthly costs. The result is the "guilt-free spend