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Less Is More

When I lead one-day AP Physics workshops, the crisis on most teachers' minds is that of limited time. The typical AP student's spare time is consumed with other difficult classes, extracurricular activities, and teenage social events. How can physics compete? A counterintuitive approach, but one which has proved successful for me, has been to turn the crisis of not enough time into an opportunity to sharply focus my class. Several years ago I carefully reinvented my Physics course so that I assigned substantially less work, and so I spent substantially less in-class time on each topic. At the same time, I heightened the level of student accountability for every element of the course. This “less is more” approach has resulted in improved AP Exam scores and skyrocketing physics enrollment.

Some of these ideas may not work for you—my personality, teaching style, and school atmosphere are different from yours. However, by picking and choosing from the ideas below, and by including some innovation of your own, you should be able to augment student satisfaction and performance, even with an insufficient schedule.

Effective Assignment of Problems

In redesigning my course, my goal was for students to do fewer homework problems, but to pay closer attention to each one. This approach has worked wonders. Students feel like they're not doing that much work compared to, say, calculus or biology; yet they do as well or better on the AP Physics Exam. Some hints about homework:

Choose problems for quality, not quantity. I now assign only one or two problems per night, but these are carefully selected. I try to make sure that problems cover material we have discussed in class, but without duplicating examples students have already seen. The assigned problems should also provoke interesting discussions. A particularly good problem might:

  • Lend itself to multiple correct approaches, such as an incline situation that can be solved either using energy conservation or Newton's laws
  • Have an answer that allows a fascinating discussion of physical reasonability, such as finding the acceleration of an electron in a television to be on the order of 1015 m/s2
  • Involve a familiar topic of interest to the students, such as a calculation of the lift provided by an 80 m2 airplane wing (and a discussion of what kind of plane might need this lift)

Use the AP free-response questions as a guide for the appropriate difficulty level for homework. I've found it counterproductive to assign simplistic plug-and-chug problems—strong students find them a waste of time, while struggling students build false confidence in their ability. Similarly, extra hard problems, even interesting ones, can cause a wave of frustration and hopelessness to spread through the class. By the end of the year, my students know exactly what kinds of problems to expect on the exam, because they've been working AP-style problems consistently all year.

Every question requires explanation. It seems that the strongest and the weakest students are most likely to give problem solving short shrift by cramming their work and answer into the corner of a page. I'm clear from day one that every problem needs a thorough presentation. Among other things, I require one full, unlined page of work per problem, including a discussion of the reasonability of the answer. Since students are only solving two problems per night, they should have plenty of time to explain their problem-solving process in detail.

Grade something every night or two. If students are not regularly held accountable for their study, then the “less is more” approach deteriorates into merely “less.” My goal is to grade one problem or quiz every night.

It is important that homework scores count somehow toward the course grade. In general, the more you grade, the more homework can be worth. (I make it 25 percent of my grade, though most teachers count it less.) But the important part is the score on each problem—if students know you are looking carefully at what they turn in, they will put forth more effort, whatever your numerical grading system.

Require extra help. If your school has an “optional” extra help period before or after school, make use of it, but don't necessarily make it optional. I automatically require a session of any student who earns less than 40 percent of the points on a problem. Such a score indicates to me that the student either didn't understand the concepts underlying the problem, in which case it is important to get them up to speed before they fall too far behind, or the student just didn't put appropriate effort into the problem, in which case an extra help session gives time to apply proper effort. Most importantly, though, assigning extra help sends a message to the class that you care about your students, and that you are serious about holding them accountable for nightly work. Every year these consultation sessions are packed for about two weeks; after that, I only have to see a few students about once per week.

Don't use class time to do homework. If you finish lecture early, it is far more useful to dig out a quick multiple-choice question to use as a “check your neighbor” exercise than to give free time to start on homework.

Foster collaboration. Time spent outside of class discussing physics with peers is often as effective as face-to-face time with the instructor. I have created an email discussion group, to which I post assignments and occasional comments on the homework. Students can also post questions, stories, or comments.

Your role in student collaboration is to encourage groups to work together effectively. It's important that all students in a group are taking part in the work; I require students to spend at least five minutes working alone on each problem before seeking assistance from anyone. Even if such a requirement is unworkable, simply grading the homework regularly is enough for you to know when a student is falling behind.

Authored by

  • Greg Jacobs
    Woodberry Forest School
    Woodberry, Virginia