Although students vary in their abilities and interests, "hyper-individualizing" the curriculum in an attempt to accommodate these differences is not the best way to help each student excel, write Willingham and Daniel. Drawing on educational research, the authors give examples of several cognitive must haves (things that the cognitive system needs to operate effectively): factual domain knowledge, practice, and feedback from a knowledgeable source. They also describe several could dos (methods that seem to work well for most students to help them meet these needs): distributing study time, practicing recalling facts, and cycling between concrete examples and abstract concepts. They conclude that to improve student achievement, teachers should teach to commonalities, not differences.