Chapter projects at the end of each chapter are assignments that can be tackled by teams of two to four students over a period of ten days or so. These forty open-ended challenges often have several reasonable solutions and no single really satisfactory solution. (Proofs, of course, are an exception.) Projects like these can provoke some deep involvement with mathematics, an experience that many students have never had, as well as requiring careful oral and/or written communication of the students' final problem statement, their analysis, and their results, depending on what you decide to assign.