Math Playground is a great website and includes many math games. The "Function Machine" game is a great resource for students to investigate the relationship between the input and output values of a function. Students are able to explore developing patterns and identify these patterns in this function machine game. Depending on your students understanding of functions there are different levels to this game, level one are simple, one step functions using the four basic operations, level two consist of two step functions, and level three consists of a mix between one and two step functions with larger values and some decimal outputs (which also allows from differentiation).
Game that allows students to find the prime factorization of a number. Assists students by giving them one factor when they correctly identify the other.