Perhaps more than any question other than "How much time should students spend doing homework?" parents and educators want to know, "What kinds of homework assignments are most effective?" Clearly, the answers to this question vary according to many factors, especially the developmental level of students and the topic area. Generally, answers are hard to find; and even for assignment variations that have been the focus of research, findings are sometimes hard to interpret. Still, a few consistent findings do emerge. A literature review reveals: (1) Studies that examined practice and preparation homework have consistently favored assigning homework for these purposes, and have suggested that distributed content may have a larger impact on delayed measurement of achievement than on immediate measurement; (2) Interspersing easy and hard problems throughout an assignment also appears to improve its effectiveness, perceived difficulty, and enjoyableness; and (3) Individualization of assignments by difficulty may have little effect on students' ultimate achievement, but preparing assignments that take into account individual students' learning styles may be more effective.