This 22-page book is a first of its kind, providing a very active introduction to Calculus with discovery-style instruction and nine student centered decoder-style worksheets. Students are motivated both by the instantaneous feedback and their inevitable success! Teachers love the improvement in comprehension as well as the ease of grading self-checking materials! Students investigate slope and average velocity to form a concept of instantaneous velocity expressed first as limits as x approaches a and then as h approaches 0. Next they derive the power rule, including using expressions with irrational constants, negative powers, roots, etc. Then they build to using the power rule when the base is a linear expression. They informally experience the chain rule and then move to more formal representations. Finally, they are introduced to the product rule, which serves as template for learning additional rules more formally.