17 July 2015

Rule 3 of teaching: Your students don't listen to you. (And a non-ohmic light bulb.)

Rule 3 of teaching, as described in the 5 Steps to a 5: AP Physics 1 teacher's manual:  Your students don't listen to you.  Don't worry, they don't listen to me, either.  

I hear regularly from physics and non-physics teachers fretting over the material they "cover" in class, over the precise content and activities they do.  I suggest taking a holistic view of a course as a whole, recognizing that students will rarely remember a specific classroom event more than a week or so later.  The College Board has gone over-the-top with this philosophy, prioritizing "science practices" and "big ideas" over content.  Their heart is in the right place.  An understanding of experimental physics isn't about "spit back the procedure, analysis, and results from this experiment you did six months ago."  It's more about, "here's a new situation that you've never seen; how would you answer a well-formed question with an experiment?"

More on-point, did you do an experiment measuring the resistance of a light bulb this year in AP Physics 1?  Did you show that the bulb's resistance changes depending on the voltage across it?  Did you have students design and carry out an experiment to determine whether, and to what extent, the bulb obeys Ohm's law?

Some of you are hanging your heads in shame, because you didn't -- and this very experiment showed up as free response problem 2 on the 2015 AP Physics 1 exam.  My big, friendly point is, don't worry about trying to match experiments with what might show up on the exam.  Not only is it an impossible fool's errand, but it doesn't even matter.

My class did this exact experiment in January.  I even made it what education professors would call an "open inquiry" exercise.  Toward the end of the circuits unit, during which we had always treated electronic devices as having constant resistance, I pointed out that some books suggest that a light bulb under some conditions might not obey Ohm's law.  It was each lab group's job to test the validity of those books' contention.

Oh what wonderful results we got!  Most groups figured out quickly and independently to graph voltage as a function of current.  You can see one of the graphs in the picture at the top of the post.  The curve is apparent as soon as you smack a ruler down on the page.  The slope varied from 51 ohms at about 2 V, to 77 ohms at about 8 V.  The bulb is non-ohmic, with a 30%-plus difference in resistance across a useful range of voltages.

Since we did such a good job with this experiment, one might expect that my students kicked arse on 2015 free response problem 2.  Um, nope.  My students performed, by far, worse on that problem compared to the others.  The College Board just released some class statistics, showing which quartile our students fell into on each of the free response problems.  On problems 1, 3, 4, and 5, the vast majority of my class performed in the top 25% nationally.  On problem 2, more than a third of my students were in the bottom half.  

Back in 2003, the same sort of thing happened in reverse.  I remember kicking myself because that was the first year ever when I didn't do an optics-bench-style experiment with my class; sure enough, that was the year when problem 4 was a laboratory-based optics bench question.  Turned out, though, my students did fine, indistinguishably from other years when I had sometimes done the very experiments that showed up on the exam.

The precise lab exercises you do don't matter.  And that's because of Rule 3. Don't take this rule as a complaint, or as the "get off my lawn" ramblings of an old man carrying on about the danged kids these days.  It's just a well-verified observation.  I see it as my job to be sure that my students succeed despite Rule 3.


12 July 2015

Do NOT allow questions during tests... repost

Never even allow a student to ask a question during a test or quiz.  This is perhaps the most important piece of teaching advice I can give.  

I am utterly convinced that your school could raise your SAT scores by 20 points across the board, and your AP math/science scores by a third of a grade, merely if your math and science departments never allowed questions during tests.

It is a dirty little secret that no one ever discusses... so many teachers talk their students through difficult problems.  No wonder those students struggle when they're faced with standardized tests, when their friendly lifeline is taken away.

I hear people argue with me, saying that they answer questions on tests because they want to help the students succeed.  Well, so do I -- and I take offense to the ridiculous connection that refusing to answer test questions equates to not caring about students.  I want my students to succeed over the time frame of their physics course.  That doesn't mean they must ace every individual test or quiz.  It is crucial that we allow our students to make mistakes, and then to learn from those mistakes.  I judge my success by how well students perform at year's end, not by whether one student got one question right on one test.

Here is the critical post explaining my approach, including some help with the issue that I know many of you already brought up, that "I could never get away with this at my school."  :-)


11 July 2015

AP Physics 1 scores 2015 -- more people passed Physics 1 than Physics B, and other commentary.

By now those of you who taught the inaugural year of AP Physics 1 have seen how their students did.  Not like the old physics B, eh?  Let's talk about the reasons for the ostensible precipitous decline in the scores.

Firstly, the raw score necessary to earn each AP grade has increased, by about 5-6% across the board.  Trinna Johnson and Trevor Packer sent a letter to the "AP Teacher Community" discussion group describing the score-setting process in tremendous detail.  In that letter, they revealed the grade cutoffs, which I've converted to percentage of available points necessary for each grade:

AP PHYSICS 1 GRADE          Percentage of available points on the test
     5                                                       71%
     4                                                       55%
     3                                                       41%
     2                                                       26%

The old physics B exam, typically, had cutoff scores of 65%-50%-35%-25%.  It takes more correct answers to pass now.

The AP Physics 1 exam, though, is considerably more difficult that Physics B.  There are no pity points available for simple calculations.  Synthesis is prized over recall.  There's no room to hide -- the questions probe for explanations rather than answers.  Due to the higher raw score cutoffs, we would expect fewer of our students to pass even on an exam of equivalent difficulty to AP Physics B. Now we have two effects that combine to reduce overall exam grades: a harder exam AND higher cutoff scores.

And finally, consider the population of students who took AP Physics 1 this year.

In 2014, 90,000 students worldwide took the AP Physics B exam; of these, 60% passed, and 14% earned 5s.  (That itself is a bit down from previous years, because the number of students taking AP B doubled over the previous decade.)  That works out to about 13,000 students earning 5s on Physics B, and 55,000 passing.

In 2015, 170,000 students took the AP Physics 1 exam -- just about double the population who previously took AP B.  Part of the intent of the redesign was to increase the pool of students who could handle an AP physics course.  Physics B was intended as a second-year course, and was so broad that it did not encourage serious, deep understanding.  Physics 1 is in fact for first-time advanced physics students.  Many schools appropriately replaced their "honors physics" courses with AP Physics 1.  Good.

But this twofold expansion in the student -- and teacher -- pool means a much broader range of student -- and teacher -- ability.  Many of the 80,000 additional students taking the exam were intrinsically weaker students.  And a bunch of teachers who were not experienced with college-level physics, or who were simply not yet capable of teaching college-level physics, were nevertheless thrown into an AP 1 course.  No wonder only 4% of the country earned 5s; no wonder only 37% passed.

Let's look at raw numbers now, not percentages.  On AP Physics 1, about 7,000 students earned 5s.  This is about half as many as earned 5s on Physics B.

But 63,000 students passed the AP Physics 1 exam -- that's considerably more than the 55,000 who passed AP Physics B  the previous year.  Even on a more difficult exam, even with higher standards for passing, more students passed this year than last.  Of course... because Physics 1 is intended as a first year course.  Sure, a bunch of folks tried this exam who weren't ready (or whose teachers weren't ready).  So what.  Thousands of folks who were ready just fine tried the new exam, and found out that they could do it.

As teachers forcibly learn that physics is about more than plugging numbers into equations, as students figure out that they can't write a bunch of baloney and expect to earn credit, AP Physics 1 scores should eventually improve.  It's on us to adjust our teaching to help these scores improve.

09 July 2015

Open Lab 2015 -- Last Call

The Manning Family Science Building, site of the Open Lab
This year's Open Lab will run Sunday to Tuesday, July 19-21, at Woodberry Forest School. Participants have requested things to do such as:

* discuss materials and laboratory ideas for conceptual physics; 

* do quantitative demonstrations and experiments with waves;

* show some options for computer simulations beyond the typical Phet; 

* set up each of the five AP Physics 1 free response problems experimentally while brainstorming short- and long-form lab exercises -- for all levels of physics class -- with these problems.

My goal is to do all these things and more, with the opportunity to improvise further with whatever equipment we have in the storeroom or the hardware store.  

The best part of any gathering of physics teachers is the shop talk and sharing.  To that end, on the first night the Woodberry Forest science department is providing dinner at my house.  Everyone's welcome; I just need to know soon if you'd like to come.  Send me an email, and I'll get you on the list.

Festivities start around 4:00 (pm, of course) on Sunday afternoon in my classroom, followed by dinner around 6:30.  Monday we'll work 8:30-4:00 or so; Tuesday we'll be done at noon.  Feel free to attend for all or part of this time.  No fees, no hassle; an email telling me your plans is the complete registration process.  You'll need to find a place to stay... I recommend the Holiday Inn Express in Orange.  Several folks will also be staying at the Doubletree in Charlottesville and carpooling up.

GCJ

06 July 2015

Mail Time: Is it "fair" to evaluate students on the quality of their homework?

As I was going through emails in preparation for the 2015 open lab (please let me know if you'd like to attend!), I found this:

I saw in your "Less is More" article that homework [was at that time] 25% of the total grade for your classes.  I was considering making homework a much lower percentage but mostly a "good faith effort completion" grade, since I've found it difficult to justify to myself grading students on their knowledge of a material while their still in the process of learning it, rather than an exam where they are reviewing the material.  What are your thoughts on this?

That's an important question for any physics teacher to be able to answer.  Remember that physics teaching is art, not science -- there are few hard truths of physics teaching, only ideas that work or do not work for each of us.  Would pointillism have worked for Picasso?  Could Rodgers and Hammerstein have written about singing cats?  Maybe, maybe not; yet pointillism and Cats! are indisputably successful things that other artists should at least be aware of.  I have my answer to the homework question that indisputably has worked wonders for me and many others.  Some good teachers may disagree with me on principle, or may choose not to use my approach in their teaching environment.  Yet everyone should acknowledge, whether they use it or not, that my approach does in fact produce considerable success for me and my students.  

To the question, then:  When you grade homework, you're not grading students on their knowledge of the material; you're grading the skill of problem solving with new concepts, along with students' diligence in seeking the correct answer.  Fact is, homework (or any work) is worthless if it's not done carefully with a full effort toward getting the correct answer and approach.  "Good faith effort completion" sounds great, but ask yourself -- if you graded students' homework carefully, would they do a better job?  Would they perform better on tests?  

My answer is, I grade homework carefully and thoroughly on a regular basis, especially early in the year.  I grade such that the students expect that their work will be judged, such that the students do their work to the highest standard they can.  And therefore, my students don't have to study for tests.  And, they perform well on those tests, because they've practiced carefully.  The one year when I didn't carefully grade homework, many students did a half-arsed job on the homework, then were upset when their test performance was poor, then complained to all who would listen that physics was too hard and that I was mean and unreasonable in my expectations, that I didn't understand my students.

As for the "fairness' issue, is it fair for the football coach to choose a starting quarterback based on his performance in practice?  I mean, practice is when players are supposed to develop their skills, right, and only the game really matters?  Yes, but everything's a test, everyone is evaluated all the time.  If you grade homework regularly -- even every other night, even only part of one problem, even a grade on a 0-1-2 scale, then you'll have enough data that one bad performance on something a student couldn't grasp quickly will be a mere blip.  

I now am counting homework and daily quizzes as half of the student's term grade, with the other half coming from monthly tests.  Not surprisingly, there is a very high -- nearly 1.0 -- correlation between homework and test grades.  I am virtually certain that the correlation between homework and test performance exists independent of how much you grade, or how much you count the grade.  The goal, therefore, is to create an incentive mechanism so that students do everything they can to get homework right.  Then test and exam performance will take care of itself.  

05 July 2015

AP Physics 1 Lab Ideas: ticker-tape machine to determine acceleration of a cart (and preparing students for open-ended labs)

Tape Timer from Sargent Welsh
The College Board has released an official lab manual for AP Physics 1 and 2.  It's important to understand that, though they call it a teacher's manual for laboratory investigations, the experiments listed are not "required" for the AP exam.  Your choice of experiments that you do in class should be based on your interest, available equipment, etc.  

The manual might be 348 pages long, but no worries.  Just read the 30 pages or so that describe the actual suggested experiments.  These are as gold to the AP physics teacher, except more practically useful than gold.  I don't suggest you use these good 30 pages exactly as described, but that you use the activities described in these 30 pages as the basis for a couple of ideas in your course.

One of the activities in the book asks students to determine whether a wind-up toy car moves with constant acceleration.  What a great question!  Acceleration by itself is a difficult enough concept, but then understanding what is meant by "constant" acceleration is tougher still.

However.  Were I to ask that open-ended question early in the year, right after finishing the kinematics unit, I'd get such poor lab performance as to make the activity worthless.  "Open inquiry," as the College Board calls it, is a waste of time if your students aren't ready for it.  An open-ended problem followed by incessant questions about what to do, followed by frustration on your and the students' part and you finally just giving them step-by-step directions, isn't really what's intended by "open inquiry."  

Students must be carefully prepared throughout the year for open-ended laboratory exercises.  Early on, you need to teach some laboratory skills that they can eventually fall back on when it's time to answer a truly free-form question in lab.  For example, using a motion detector to measure distance, instantaneous speed, and acceleration is a skill that students must be taught.  Similarly, it's important to get your class practice in using photogates, spring scales, video analysis, ammeters and voltmeters, and other basic equipment.  I'm not suggesting one of those beginning of the year "let's measure a bunch of random stuff and talk about error" exercises, I'm suggesting that you teach such skills in context.  Do demonstrations with this equipment.  Have students use the equipment to verify the answers to homework problems.  Do a long-form lab with graph linearization where they must use equipment for multiple-data-point collection.  

Want a practical example of the difference between an early-year experiment and a late-year experiment?  

Here's the early-year version:  I have students release a PASCO cart from rest on an inclined track.  They use a tape-timer* to get the position of the cart 60 times per second.  Graphing the cart's position every 6th dot** makes a position-time graph with 0.1 s precision.

* You can buy such a timer from PASCO for $180, or you can get the cheap version from Sargent Welsh for $17.  The cheap version works fine.

** Why only every 6th dot?  Because we can decimalize every 6/60 of a second into 0.1, 0.2, 0.3 s.  Trying to graph every 1/60 of a second leads to numerical confusion, the graph taking ten times as long to make, and incorrect accelerations.  Thanks to Curtis Phillips for pointing this easy trick out to me after I had struggled with the graphical analysis of this experiment for nigh on two decades.

Next, I have students take the slope of two tangent lines to find two instantaneous speeds.  The change in speed divided by the time it took for the speed to change is the cart's acceleration.  You can see here the homework assignment that students fill out.  I determine the "theoretical acceleration" by measuring the angle of each group's track with an angle indicator, and using gsinĪø.

This experiment takes a full 90-minute lab period plus a night's homework assignment to complete.

Then the late-year version:  In the last month of the course, I assign the homework problem with a direct measurement video that you can read here.  Everyone can view the video, then determine for himself how he's going to check for constant acceleration.  No one really, truly remembers the tape timer experiment from October.  However, they now have a reasonable understanding of what acceleration is, and they have used multiple methods of finding instantaneous speeds all year.

This assignment provoked such a wonderful in-class discussion.  Some folks compared the change in speed over two time intervals.  Others used four time intervals.  Some made a velocity-time graph for four or eight data points and looked for a straight line.  An argument ensued as to what the distance scale on the video was; a student pointed out that it didn't matter, as arbitrary distance units work just fine to answer the question.  The one confused student who confused speed and acceleration discovered his mistake quickly and authentically, without me having to say a word.

In other words, at the end of the course, my class not only could perform a complicated, creative experimental task... they had the skills to discuss the merits of different methods.  That's the holy grail of introductory physics laboratory work.  But, searching for the literal Holy Grail requires a long, difficult journey filled with peril.  Don't expect to hold the grail immediately -- guide your class through the journey.  Can't I have just a bit more peril?


04 July 2015

AP Physics 1 lab ideas: Spring constant of a hopping spring toy

spring toy available
from Oriental Trading
For the first time in ten months I'm not in constant preparation mode -- preparation for class, for workshops, for the USIYPT, for department meetings... I have a few weeks off with no immediate obligations.  Now is a good time to take stock of the activities I used in my first year of teaching AP Physics 1.

My advice about laboratory in AP Physics 1 is to teach the material up front and quickly, such that students know and can use basic facts, equations, and problem solving techniques.  Then do experimental work.  Set up problems you've solved for homework or on quizzes as laboratory activities.  Some of these will be quick and dirty -- did the speed at the bottom of the hill double when the hill's height quadrupled?  Some will be more involved, with extensive data collection and graphical analysis.  

Over the next few posts, I'll describe some of the extensive, long-form laboratory activities I used this year that were successful.  Many of these are based on old AP Physics B questions.  I'd suggest that scouring the released AP Physics B free response questions since 1996 could provide a fantastic lab manual for any advanced physics course.  

Today's experiment comes directly from the 2009 AP Physics B exam problem 1.  I show the class how the pictured pop-up spring toy works: push it down, and when the suction cup loses suckiness, the toy pops up.  I show them that we can use flexible aluminum wire wrapped around the top to change the toy's mass while still allowing it to pop up.  I ask them to graph the height to which the toy pops as a function of the toy's mass.  As always, I give no handout with instructions or prompts.  Each group is to produce and turn in a raw graph of the experimental data along with a data table.

When I'm satisfied with the data collection, I xerox the data tables so that each student in the group has his own copy.  Then I hand out the linked homework assignment.  Each individual student now must linearize the graph, take the slope, and use the slope to determine the spring constant of the toy.  
Before you try this experiment, be sure you've done at least two or three graph linearization experiments, and be sure everyone can deal with basic energy conversion problems.  I never did assign the official 2009 AP Physics B problem.  However, if you use that problem on a test, then this experiment could be a perfect follow-up.  Or, do the experiment in November, and put the 2009 problem on the semester exam in late January.*

* That's not as crazy as it sounds.  Students don't remember your lab exercises as much as you think.  For example, my class did the "does a light bulb obey ohm's law?" experiment this year, with everyone making a graph of voltage vs. current to see if the slope was constant.  Nevertheless, when we debriefed and discussed the 2015 AP Physics 1 free response, no one at all mentioned that we had done that very experiment.  Most of my students got it essentially right, but without the elegant graphical solution -- they said they checked several times to see if the V/I ratio was constant.  That's Rule 3 of teaching: Your students don't listen to you.  (But no worries, they don't listen to me, either.)


27 June 2015

Get class started right away -- no silly questions, no individual discussions

So many physics teachers would like more contact time with their students.  Sounds great, but don't count on administrative fiat giving you exactly the schedule you want anytime soon.  You don't make scheduling decisions, and be glad you don't, because everyone is somehow unhappy with every academic schedule ever devised.

The best solution to a schedule you don't like is to make the most of every moment you are allotted.  Don't stop physics work ten minutes early because you finished your planned activity -- instead, have a TIPERS or some sort of check-your-neighbor activity ready for just such an occasion.  Start class when the bell rings, not when everyone has finished their conversations and meandered to their seats.

Starting class promptly is a tricky exercise.  You don't want to be the officious arse who metes out punishment by caning* to those who show up a moment late.  But without careful attention to the start of class, human nature means that you'll be getting down to business later and later as the year moves along.

* figuratively.  I hope.

Routine is your friend.  My personal preference is a two-to-four-minute quiz to start every class.  Not only does the quiz provide a better review than any amount of me talking at the class, the act of me saying "begin the quiz" and starting the countdown timer sends the message that class has started.  No nagging, whining, begging, lecturing, or caning is ever necessary on my part.  Because this opening quiz is an immutable routine, students adapt without complaint or comment.  When someone is slightly late, there's no discussion or excuse, because the latecomer races to get as much of the quiz done as possible.

But there's more to starting class on time than beginning the quiz.  As students enter the room, you'll often hear a cacophony worthy of an elephant seal rookery.  "Mr. Lipshutz, did you grade last night's problems?  Can you help me with this solution?  Did we have homework?  What are we doing in class today?"  

Aarrgh!  I don't want to be unfriendly, but (a) I want to start on time, and (b) I don't want to encourage dumb questions by answering them.   And most any attempt to address a silly question at face value does in fact beget more of the same.  If I graded the homework, it will be in your work-return box, just like it was every other day this year.  I would be happy to help you with solutions, but not two minutes before class time, as we've discussed before.  We have homework every night, and if you aren't sure about the assignment, what are you going to do about that in the next two minutes?.  You'll find out in class -- you know, the class that starts in two minutes -- what we're doing in class today.  I give these non-answers -- politely the first couple of times, with emphatic finality if they continue more than a couple of days in a row -- along with a reminder to get problems out and prepare for the quiz.  The dumb questions disappear pretty quickly, often when a student starts sarcastically giving my answers to his slow-witted peers.

Okay, that's how to handle the ridiculous questions.  But what about the important or reasonable questions?  You don't want to answer those right before class, either.  It's so, so easy to get caught up in a five minute discussion with the diligent student who will be missing two days of class next week, and wants to plan how to catch up.  That's a conversation that must be had -- but it doesn't have to happen now.  Don't make your class sit and wait for your conversation to finish, just like you don't want a store clerk to make you wait to check out while he and the manager discuss important issues about the end of tonight's shift.  Ask the student to come by after class, at lunch, or some other time.  Whatever reasonable questions there might be from individuals, they can all be dealt with later.  Get class started.

Two time-saving answers to common beginning-of-class questions I learned from colleagues at the AP reading:

(1) Hey, I missed yesterday's quiz because I was absent.  When can I make it up?  Don't bother... we'll just have tomorrow's count double.  Aha!  No more tracking down people for make-up quizzes.  And since I give a quiz every day, even really good or really bad performance isn't going to change anyone's grade significantly.  It saves me trouble, but also, what incentive to keep up!

(2) On problem two of this test, you took off two points, but I think you only should have taken off one point.  Let me show you what I meant.  Not now.  But if you'll place your test in this folder, I will be glad to carefully regrade the ENTIRE test tonight.  What is the probability that this student actually bothers to re-submit the test?  Chances are, the student is grasping at straws hoping to use debate skills to convince you of something.  And this student also knows in his heart that if you go through his test again with a fine toothed comb, you might find one or two other places where he didn't deserve awarded points.  You've arranged a perfect result, then -- if you truly made an egregious error, you'll be able to correct it, but you provide a disincentive to those who are merely whining.

Do you know a polite yet firm answer to a typical opening-of-class question that avoids protracted conversation?  If so, let us all know in the comments.


17 June 2015

Official Course Descriptions for all Woodberry's Physics Offerings

I'm often asked about Woodberry Forest's physics curriculum.  We require all students to take a full-year physics course during high school.  Those who enter as 9th graders take physics first.  Those who enter in 10th or 11th grade usually take physics in the junior year.  Below are all of our course descriptions, as published in Woodberry's course catalog.  

Nomenclature note: "3rd form" refers to 9th grade, "6th form" to 12th grade.  "Form" is archaic terminology referencing the benches in which students in olden-days Harry-Potter-Style boarding schools used to arrange themselves by class.  What we call the seventh grade sat in the first benches, and so was referred to as the 1st form.  

Feel free to email with questions and comments.  If you come to a summer institute or to the open lab, I can give you a CD-rom with tests, quizzes, and problem sets for each of the courses listed below.

GCJ

Conceptual Physics
Conceptual Physics, the year-long, third-form science course, emphasizes the principles of physics on a conceptual basis.   The course begins with optics and waves and progresses through electric circuits before covering traditional mechanics topics. Students use the fundamental facts and equations of introductory physics as a vehicle for a thorough introduction to analytical thinking and creative problem-solving skills.

Approximately 50% of class time involves hands-on experimental work.  Nightly problems require students to justify their answers with substantial verbal reasoning.  Tests and exams questions are based on authentic items from New York Regents exams, adapted such that a calculator is not required, and adapted to require students to demonstrate their verbal as well as mathematical skills.  It is expected that a successful conceptual physics student leaves with a solid understanding of qualitative mathematical approaches to problem-solving, including verbal justifications of answers; graphical analysis, both experimental and theoretical; order of magnitude estimation, including describing the physical meaning of numerical answers; and experimental verification and investigation of physical relationships.

Physics
Physics is a year-long course appropriate for upper-form students with a background in algebra and lab sciences. The course approaches the same topics covered in the 3rd form Conceptual Physics course, with more emphasis on working qualitatively with physical concepts. The course begins with a study of mechanics, including kinematics, Newton’s laws, and the conservations of energy and momentum. Later topics include circuits, waves, and optics.

Students spend a significant amount of class time doing hands-on experimentation, developing an understanding of how to use experimentation to make or verify physical predictions. Other time is spent learning and discussing physics principles, and practicing their application in problem solving and justification. Homework consists of readings and problem sets, with an emphasis on logical, verbal reasoning. Tests and exams are based on New York Regents exam questions.

It is expected that a successful student in General Physics leaves with a solid understanding of qualitative and quantitative mathematical approaches to problem-solving, including logical justifications of answers; experimental and theoretical graphical analysis; order of magnitude estimation, including describing the physical meaning of numerical answers; and experimental verification and investigation of physical relationships.


Honors Physics 1
Honors Physics 1 follows the course description for AP Physics 1: Algebra-Based provided by the College Board. This is an algebra-based, college-level survey course, covering important topics in classical physics. Students are expected to develop both a mathematical and conceptual understanding of the subject, with a substantial emphasis on the latter.  The course is taught through the use of quantitative demonstrations and in-class laboratory exercises, paired with nightly assignments involving descriptive problem solving.  In weekly extended laboratory sessions, students design experiments to investigate the principles discussed throughout the course.

Tests and exams are in the style of the AP Physics 1 exam.  Students are encouraged to take the AP Physics 1 exam in May.  Honors Physics 1 is taught to three constituencies of students who may opt in: Any 12th grader who is interested, 11th graders who have completed a high school biology course or who are taking biology concurrently, and a set of 9th graders who are selected by the department during the first marking period.  The separate 9th grade section covers the identical material at the same college level.

Honors Physics 2
Honors Physics 2 follows the course description for AP Physics 2: Algebra-Based as provided by the College Board, along with a few additional topics. This is an algebra-based, college-level survey course, covering topics in fluid mechanics, thermodynamics, electromagnetism, atomic and nuclear physics.  Students are expected to develop both a mathematical and conceptual understanding of the subject. The course is taught through the use of quantitative demonstrations, paired with nightly assignments involving descriptive problem solving.  In weekly laboratory sessions, students design experiments to investigate the principles discussed throughout the course. Honors Physics 2 is primarily a senior course.  Honors Physics 1, or a placement test showing mastery of the skills and material covered in Honors Physics 1, is the required prerequisite.


Honors Research Physics and Physics C
From September until February, students research four problems in preparation for the US Invitational Young Physicist Tournament (USIYPT).  Faculty and students together investigate these open-ended, college-level projects.  A solid grasp of theory and intricate, involved experimental work is required.  The trimester exam is a 5-10-minute talk based on the research project.  As the tournament approaches, students are trained to conduct a “physics fight,” a ritualized debate over the merits of a solution.  Four members of the class are selected to be representatives of Woodberry Forest at the USIYPT.


Throughout the year students prepare for the AP Physics C – Mechanics or AP Physics C – Electricity & Magnetism exam, using the course description provided by the College Board.  Calculus-based mechanics or E&M is covered through nightly problem-solving as well as in-class review, demonstration, and discussion. Students are expected to develop both a mathematical and conceptual understanding of the subject so as to perform well on the May AP exam.  The physics faculty will in the spring select approximately eight students, including mostly rising seniors but also some rising juniors, to audition for Research Physics. The invitations are issued based on performance in previous science courses, and based on the skills and background knowledge each student could bring to the competitive physics team at the tournament.  The audition consists of a preliminary investigation into one of the USIYPT problems in the last weeks of May, followed by a presentation to the faculty during exam period.  Students must be invited to and pass the audition in order to take the course.

16 June 2015

Set up *ALL* AP Physics 1 problems in the laboratory.

"Laboratory" doesn't have to be a distinct part of a physics course -- it's just what we do, especially in AP Physics 1.

When I took high school and college science classes, "laboratory" was a special, separate portion of each class.  Most days the teacher would talk to us about facts and problem solving.  Once a week or so we would perform an experiment -- always going to a separate lab room in order to do so.  The laboratory portion of the course stood entirely separate, too, in terms of evaluation.  The idea of asking a test question in an experimental context was utterly foreign.  Sure, biology had "lab practical" tests in which we identified parts of a frog or worm*.  Those tests were still entirely in the experimental realm, just an alternative to a lab report.  A holistic integration of facts, problem solving, and experimentation was unheard of.

* Gross.  Now you know why I'm a physicist, not a biologist.

In the mid 1990s the AP Physics exams began including one question per exam based around an experiment.  Such questions required explanations of procedure as well as verbal and quantitative analysis of data.  I've often recommended to teachers that they could use these old test questions essentially as a laboratory course -- assign the AP questions on quizzes or tests, then use lab time to actually do the experiment.  

The AP Physics 1 exam also includes one free response question related explicitly to laboratory skills.  On the 2015 exam, that was question 2, about circuits.  It would be a simple matter to repurpose this question as a laboratory activity.  The first part asks for simple ammeter and voltmeter readings.  The second part asks students to determine whether a light bulb is ohmic -- my class did this exact experiment, graphing current vs. voltage, and found a clear curve.  

The hugely important point is, all five of the 2015 AP Physics 1 free response questions can be set up as laboratory activities.  

Question 1 asks for a qualitative prediction of how the acceleration of an Atwood's machine will change with added mass.  So set the situation up with two pulleys on a lab table, and use a motion detector to measure the acceleration with and without a cart included in the system.  

Question 3 puts a block on a horizontal spring, and asks for a graph of kinetic energy vs. time for the block as it leaves the spring and slides to a stop.  Use a compressible spring and a rough block on a track; a motion detector can record position and velocity data.  Vernier Labquests can be easily programmed to graph kinetic energy as a function of position, as on the test question.

Question 4 is the classic "does a fired bullet hit the ground at the same time as one that's dropped?"  Video analysis of this phenomenon is readily available.  A Mythbusters* episode was devoted to exactly this problem.  I use the ipad app "Coach's Eye" to record my PASCO projectile launcher shooting balls horizontally at different speeds.  The app shows conclusively that the balls hit the ground within a hundredth of a second of each other.

* Or perhaps it was a "Ghostbusters" episode.  Some students might have been confused on this account.

Question 5 is basically asking why each string on a cello or guitar plays a different note when plucked.  You could get some guitar strings and set them up over pulleys, exactly as in the problem. Then you could pose exactly the AP question as an open-ended, live-action laboratory activity.  No description necessary, though, just "Look here, why do these four strings play different notes?  Explain, and then do some sort of experimental test to see if your explanation is correct."

Last year in one of my summer institutes, we spent a morning setting up experiments to verify the answer to multiple choice questions on the released practice exam.  We found a way to do most of them.

The beauty of AP Physics 1 is that, with very few exceptions, all of the relevant topics lend themselves to classroom-scale experimental investigations.  They don't all have to be done as student-led, hands-on, multi-day laboratory activities, of course.  You can do quantitative and qualitative demonstrations from the front of the classroom.  You can have students make "quick and dirty" measurements sometimes rather than detailed graphs over a large parameter space.  You can collect and analyze data occasionally as a whole class rather than in individual lab groups.  

But you can and should do the experiments suggested by virtually every problem in AP Physics 1.  Fortunately, for me, the days of having one room for lecture and another for lab are long gone.  I don't teach a separate lab course, though we do perform a few extensive, multi-period projects along with quicker investigations.  My goal is to get student hands on equipment about three times per week, even if only for a few minutes on some of those days.

And what is my lab guide for all those 100 plus lab days?  Much of it is just the released AP Physics exams themselves.