# Focused Use of Class Time

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## Tips for Efficiency Without Cramming

Students have access to all kinds of AP Physics resources, including their text, the web, classmates, and AP prep books. These are available all the time. But the most important resource is the instructor, who is only available during class (and extra help sessions). Though it is important to maintain a relaxed, comfortable classroom atmosphere, it's also necessary for you to incorporate lectures, discussion, labs, demonstrations, and problem solving into class time.

Preparation is critical. Each class certainly doesn't have to be planned to the minute; but if you have a solid idea of what needs to be accomplished each day, and if you communicate that vision to your students, you'll stay on pace. Some hints for quality use of in-class time:

Combine demonstrations and sample problems. Students love demonstrations—they're attention grabbers. But I also usually include a quantitative element to demonstrations, so that the demonstration serves as an example of a typical problem.

For example, I explain the concept of a “normal force” using a toy bus on an incline. First we calculate the normal force on the bus by measuring the angle of the incline and the weight of the bus. Then I show that the bus remains unmoved if the incline is replaced by a rope pulling perpendicular to the plane with a tension equal to the normal force that we calculated. The class sees graphically that the answer to a problem is not just a number, but a quantity with physical meaning. Just as importantly, I have reduced two lecture elements (the example problem calculating the normal force, and the conceptual demonstration of normal force) into one quicker element.

Resist most calls to "go over the homework." Occasional discussion of a particularly interesting or confusing homework problem is useful and important; but don't feel obligated to go over problems regularly. Post solutions on an accessible bulletin board, and suggest that the students go over the problems with one another. Extra help time outside of class is the appropriate place for discussing a single student's specific question about homework.

Set a yearlong schedule, and let that drive the pace of problem assignments. Let the daily problem assignments drive the pace of each individual class. I hand students a schedule of homework assignments each week. Then, the students and I both know that each class must cover at least the material for that night's problems. Each week, though, I have the chance to slow or speed the pace by choosing the next set of problems.

Skip minor parts of topics.You don't have to cover it just because it's in the text! To know what's “minor,” look at some recent released exams. For example, I don't introduce quantitative aspects of the Doppler effect. I ask the students to read that section, and I may give some conceptual examples for five minutes one day at the end of class. I don't recall more than one Doppler effect computation in the last two decades of exams, and that was on the multiple-choice; so I'm comfortable with my approach.

That said, don’t skip entire topics. For example, one year at the AP Reading it was apparent that some teachers chose to skip double slit-style situations entirely. Many of their students were so frustrated that they failed to get points for the easy parts of the problem that had nothing to do with a double slit! The effect on a student who is faced with a completely unfamiliar free-response item goes beyond the mere loss of points for that particular problem, as their confidence and mental approach have been compromised.

If you are careful in your choices, incomplete coverage can work just fine. Just be sure your students know what you're skipping and why, and be sure they know how to approach unfamiliar problems to earn partial credit.

Use laboratory activities to reinforce other physics skills. Students could experimentally verify the answer to a homework problem, investigate a phenomenon as a prelude to hearing a quantitative treatment, or design an experiment posed as an AP-style lab question. In fact, I have occasionally used a previous year's experimental question on a test, and then used that same question as the basis for the next laboratory activity.

## Authored by

• Greg Jacobs
Woodberry Forest School
Woodberry, Virginia