Mathscribe is free software for graphing, modeling, equation solving, formula editing, etc. for algebra, trigonometry, and precalculus students. It calculates and graphs elementary functions (ones formed from polynomial, rational, algebraic, trigonometric, exponential, and logarithmic functions). The student can vary a parameter's value simply by clicking or dragging on a slider, and a graph will immediately be updated. The site also provides free algebra lesson plans for use in a computer lab.