The main purpose of a fifth-grade math projects is, of course, to teach the children how to do math. Mathematical concepts are important for many reasons. Fractions and decimals allow children to understand statistics, money and other real-world numerical concepts. Consider teaching these concepts by assigning projects that use these tangible applications. Some fifth-grade students may even receive an allowance from their parents. Projects that involve money may plant the seeds for valuable financial lessons that will last children into adulthood.
Another concept that is generally found on fifth-grade mathematical curricula is probabilities and odds. Projects that simulate the experience of gambling --- with fake money, of course --- can teach probability and odds very effectively. These projects may also tie in with lessons on decimals and percentages.
Graphing and measurement help kids learn how to read maps, statistics and other numerical data made tangible by translating it into a visual medium. Projects involving maps have the added benefit of instilling a sense of distance and size into kids at an early age. This may lead to the ability to estimate distances with reasonable accuracy, as well as translate a distance on a map to a real-world distance.
Perhaps the most important purpose of fifth-grade math projects is to make difficult concepts seem easy. Since pure math is intangible --- unlike science or history --- it is often difficult for young minds to grasp. Translating it into something that fifth graders can wrap their heads around and figure out for themselves bolsters their confidence and lays a foundation for good work habits to come.