Homework is an integral component of most science courses but can have an impact on student learning only when students actually complete the assignment. Low completion rate of homework, then, is an impediment to student success in science courses, and a source of frustration for instructor and students alike. Here, we outline a set of design principles supported by research in how students learn, intended to streamline outside-of-class assignments to address course goals, improve student buy-in and motivation, and provide instructors better formative assessment data. We also share examples of outside-of-class assignments aligned to these principles to aid instructors in shortening and focusing the homework they choose to assign in their courses.