For many people the best indicator of rigor is the amount of homework required of students. Some teachers pride themselves on the amount of homework expected of their students, and there are parents who judge teachers by homework quantity.
Realistically, all homework is not equally useful. Some of it is just busywork, assigned by teachers because principals or parents expect it. One study (Wasserstein, 1995) found that students described busywork as unimportant, and therefore, not satisfying. Contrary to what many adults believe, the study found that students viewed hard work as important and enjoyed the challenge and enjoyment that went with accomplishing a task that was hard.
For some students, doing more homework in terms of quantity leads to burnout. When that occurs, students are less likely to complete homework, and may be discouraged about any learning activity.
“Doing more” often means doing more low-level activities, frequently repetitions of things already learned. Such narrow and rigid approaches to learning do not define a rigorous classroom. Students learn in many different ways. Just as instruction must vary to meet the individual needs of students, so must homework. Rigorous and challenging learning experiences will vary with the student. Their design will vary; as will their duration. Ultimately, it is the quality of the assignment that makes a difference in terms of rigor.