This mid-level combinatorics textbook was originally written to be used in a MA level course for current secondary math teachers. Topics have been selected to illustrate larger concepts of interest to secondary teachers, and would also be appropriate for an upper-level undergraduate course for future teachers. There is an emphasis on understanding simple concepts deeply and in more than one way. Although some topics intersect secondary curriculum, most of the questions here are at a higher level. Still, the problem solving strategies and big ideas illustrated by our questions have applications to secondary mathematics. This emphasis is quite different than other mid-level discrete and combinatorics textbooks, since the goal is not to prepare readers to begin a career in research mathematics.

Little is assumed about the reader's previous work in the subject, beyond a general understanding of how abstract mathematics proceeds, as well as some basic ability with mathematical proof. For the reader completely unfamiliar with these and the basic objects of mathematical study (sets and functions), background material is included in an Appendix.

While the book does not address how to teach mathematics, it tries to model good pedagogical practice. Almost all of the textbook consists of Activities and Exercises that guide readers to discover mathematics for themselves. This will require quite a bit more work, both from students and instructors, but the authors strongly believe that the best way to learn mathematics is by doing mathematics. Most of all, discovering mathematics is fun.