Problem solving is an essential skill. Confident problem solvers can identify and frame a problem productively, they have strategies to help them approach the problem, and they can assess whether their solution strategy is successful. Rigorous mathematics instruction includes a strong focus on applications of mathematics; these applications are often grounded in problem solving. Problem-solving tasks can occur in real-world contexts or in mathematical contexts. In either case, collaboration and discourse is essential for problem solving. The more complex the problem, the more important multiple perspectives are in finding a good solution. Selecting appropriate tasks and facilitating productive collaboration and discourse are critical teacher skills for supporting problem solving in the classroom.