My AP Calculus colleague Julianne Shanblatt wrote this set of 16 exercises for her precalculus students to gain practice with that famous difference quotient:
(f(x+h) - f(x))/h. Students begin in the first cell, work the problem, and then hunt for their answer. That becomes the second problem. Then they continue in this manner until they close (or complete) the circuit. All functions are covered, constant, linear, quadratic, cubic, trig, exponential, rational, and square root. This circuit will really make your students flex their algebra muscles. Alternatively, this set of exercises would make terrific guided notes.