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07 September 2017

How should a physics teacher use a "learning management system"?

A reader indicated that he's being pushed by his administration toward using the learning management system Canvas, especially for paperless testing.  Where do I stand, he asked?

My school adopted Canvas about four years ago.  While I'm not personally a fan, I recognize and acknowledge the major benefit to the student, especially the student at a day school.  All assigned work is clearly indicated on and accessible from a simple-to-use calendar.   Student misses a day of class - no worries, assignments are on Canvas.  Student is disorganized and loses assignment sheet, or forgets where to look online for my assignment - no worries, all on the Canvas calendar.  

My concern is partly that we are doing a large amount of organization for the student, rather than the student internalizing the organization skills for him- or herself; my concern is partly that significant technical hurdles to uploading and downloading assignments too often get in the way of teaching.  Nevertheless, in these matters I yield my own judgment to the consensus of our faculty.  Canvas has in general been a positive development for us.

I do not yield my judgment about physics teaching.  Physics teaching is different from teaching other subjects, and way too many people don't recognize that.  

It sounds like this reader's administration isn't considering how physics is done.  Yes, in some classes at my school, essentially all assignments and tests are handed out and submitted through Canvas.  That works fine for multiple choice, for pure text in an English or history paper, for straight-up numerical responses.  

As you indicated, though, physics demands communication in writing.  A well-presented problem consists of words, diagrams, equations, and numbers.  Annotated calculations or derivations often include circles and arrows and, well, handwriting techniques that I can't well describe or draw in a blog post.  I'd need hard copy.  

And so, when I create assignments in Canvas, I simply attach a file consisting of the problem set questions.  The actual assignment submission is always on unlined paper.  Canvas is still an important and useful tool, though, ensuring that everyone has the assignments available electronically in calendar format.

It is NOT POSSIBLE to appropriately test physics students using Canvas, or using any computer input.  Physics assignments require paper.  They require pen or pencil, and sometimes ruler and protractor, graphs, the ability to create or annotate diagrams, to draw and refer to pictures... 

If administrative fiat demands that you use Canvas for the multiple choice portion of your tests, so be it... I mean, multiple choice is multiple choice.  But for the free response homework and tests, I encourage the entire physics teaching community to continue to require hard copy.*  To do otherwise, I think, is professional malpractice for a physics teacher.

* Okay, okay, if you have a seamlessly working tablet with a stylus for everyone, perhaps that could work, 'cause that's the same input method as paper.

When the administration similarly requires computer tests and projects in your Studio Art class, then perhaps I'd reconsider.  Perhaps.  :-)

03 September 2017

Can I go to the bathroom?

Of course.  In the future, please don't ask... 

Just place your phone on your desk and go.

23 August 2017

What does good learning look like?

Our faculty has been discussing the excellent book What the Best College Professors Do.  Until today, we've been focused on what good teaching looks like.

The focus shifted today.  We were asked to write, "what does good learning at our school look like?"  Here's my response, written for an audience of teachers, but not science teachers.  

I speak to science in particular.  Yet, my hope, and the hope of the science department, is that an evidence-based model of learning becomes an innate part of a student’s personality, something that goes on without conscious thought.

In pursuit of the goal, one activity that I’ve done with all ages of student aims to get students to evaluate pseudoscientific claims that they have likely heard repeated as gospel.  Everyone is given a “quiz” on which they mark a number of statements true or false.  Next, they are asked to research in depth a statement they marked as true, treating the claim as scientific.  A scientific claim is false by default – it only acquires the status of “true” once diverse and compelling evidence supporting the claim can be produced.  So, students are charged to lay out for me, as a representative of the scientific community, evidence supporting the claim; or, conversely, to acknowledge that he claim is false and to give me background explaining why some folks might think it true.

For the purpose of describing great learning at our particular boys' boarding school, I’ll use one of the claims from this activity:

Human women have one more rib than do human men.

(1) Great learning begins with an interesting, yet answerable and in-scope, question.  

It’s the teacher’s job to help present and refine relevant questions, especially for younger students – “how can I build a working nuclear missile” is interesting and perhaps relevant, but out-of-scope for most of our classes.

How do I know this particular question about ribs is interesting?  I observe students marking it both true and false; I observe spontaneous initial discussions among classmates explaining their thoughts.  They seem to care about the answer.

(2) Great learning means searching not for the direct answer to the question, but rather for evidence with which to answer the question.  

Note that the research portion of this project doesn’t say just “find an expert who tells us the answer.”  No, students are to look for evidence.  It’s important that I don’t shame the students who marked this true by telling them, as the authority figure, that they’re wrong.  It’s also important that they don’t just quote their 1st grade Sunday School teacher as the authority.  They must find their own evidence.  
In researching the rib question, students have found online pictures of x-rays.  They’ve discussed with the school trainer.  One student asked a young lady if he might please feel her ribs.  All’s fair in the pursuit of science, I say.

(3) Great learning continues by evaluating the quality of evidence.  

For many questions, students find that the top google hit is Big Bob’s Website of Dubious Rigor.  I usally don’t have to explain much to students, even 9th graders, about what a reliable or unreliable website looks like.  That they have to present quality evidence to me in person keeps most ridiculousness away.  Because they are asked for evidence, not authority, they stay away from slick, shallow, yet plausible-sounding sites.  Because they have to present in person to me, they are careful to be intellectually honest.  It’s one thing to use Sean-Spicer-logic on dorm or on twitter; it’s another thing to state clearly disingenuous baloney to a science teacher in the front of the classroom.

When a student does have a legitimate misunderstanding of a claim, I argue about quality of evidence, not about the conclusion.  Students take it personally if I question, in this case, their adherence to the literal truth of the bible.  Yet, they respect and acknowledge my request for more diverse evidence: “A scientific claim requires an abundance of clear evidence from multiple sources before we say it’s true. What sort of evidence could you find that would convince not Big Bob or you, but that would convince me and other scientists?”

(4) Great learning requires a continual re-evaluation of one’s model of how the world works.

Virtually all of the claims on the quiz are false; but generally students mark about half of them true.  The beauty of this exercise is that the students have confronted their misconceptions for themselves, in front of their peers.  I hear them telling classmates what they’ve discovered: “Yeah, my dad said that women have more ribs, but I saw the x-rays.  It’s not true.”  “Yeah, my cousin used to campaign against vaccines; but they don’t cause autism, that’s been debunked.”

Overhearing those conversations is a piece of evidence I use to see that this exercise has produced great learning.

17 August 2017

Mail Time: What if I have to miss the first week or two of school?

A reader will be unavoidably absent until the second week of school.  The question to me: What would I do with an AP Physics 1 class, knowing that the sub is a random adult rather than a physics teacher?

Of all the times you'd have to miss.  Guh, not the first week(s) of school.  This is when physics students most need your guidance.

I don't have an easy answer for this one.  I'd really rather just start school two weeks late than have a random sub for a week.  It's too easy for bad habits to get ingrained, for them to get a false sense of what physics is. 

But I'll bet your school isn't about to cancel physics class for two weeks.  My only suggestion would be to do unrelated enrichment work for a week or two, and then start the course as normal when you return.  See, I think many of us take time out during the school year, or perhaps after the AP exam, to do some one-off activities: a bridge building contest, research about the history of science, etc.

It's not ideal... but you could move some one-off activities to the start of the year.  It's important to choose activities that are not directly related to physics content, I think, so you don't ingrain misconceptions.  So those projects about motion picture physics, or making a video about a physics concept - I don't recommend at year's beginning.  I offer two options that I've done in the past that might be useful here.  I suspect this post's comment section might provide even better ideas.

Option 1: Here is a link to a "pseudoscience" activity I've often done at year's end... they take it as a quiz, then they choose one or two things they marked true to investigate.  In science, all claims are false unless clear evidence is presented to convince an audience they are true. This activity can be done with minimal supervision; the students will discuss well with each other.  Give a few suggested sites to jump-start student research, such as snopes, the straight dope, and the skeptical inquirer.  

Option 2: Pose some astronomy questions, and have students investigate them using some online tools.  I like the Regents earth science astronomy questions, paired with a University of Nebraska set of simulations.   Just pick some of the questions from recent tests about observational astronomy, the motion of the sun and moon, or the phases of the moon; then ask students to teach themselves the underlying geometry using the simulations.  If you email me, I can forward you a few assignments I've given using this method.

Other than that, I don't know.  I seriously don't recommend lab work or math review.  I don't recommend any physics content at all until you're there.  I'd love to hear good ideas in the comments.  Best of luck.

26 July 2017

Methods of in-class collaborative work: 421

This weekend I attended a workshop given by Kelly O'Shea and Danny Doucette.  They showed us their outstanding approach to lab practicals, which they assign as group tests.  

The discussion in the room at several points turned to balancing the group / individual dynamic in the classroom.  On one hand, physics is a collaborative endeavor. Cooperation and communication are skills which we must teach and assess.  On the other hand, we are teaching result-obsessed teenagers, who default to letting the (perceived) smart kids do all the work, probably while making fun of them behind their back.  

If we're going to encourage, let alone require, cooperative work in physics class, we must incentivize appropriate collaboration.  Remember, incentives can and should take forms other than mere grades.  Although others have found success in assigning a direct grade for the quality of participation in group work, I have not; I find students spend more time gaming the grade than actually collaborating.

My personal approach to encouraging effective collaboration is enforcement of the five foot rule.  As always, my way is not the only way.  Another workshop attendee -- I dearly wish I remember who -- mentioned an extraordinarily clever approach to evaluated group work, one that I'd like to try.

He called it the 421 method.  The laboratory exercise or problem to be solved is presented to the class, and then the class is divided randomly into groups of four.  Then, work proceeds in three stages, with clear time limits assigned to each.  (Yes, stages are numbered strangely.  You'll see.)

Stage 4: Discussion.  Each assigned group of four may discuss the problem together; but they may not write anything down.  No pen, no whiteboard, nothing.

Stage 2: Representation.  The groups are subdivided into pairs.  Each pair may communicate orally and using a whiteboard.  However, they may only write representations - no numbers or words.  This means they can use equations, free-body diagrams, energy bar charts, etc.  

Stage 1: Solution.  Now students separate to use pen and paper.  They are assigned to write a thorough response, including representations, numbers and words.  This is turned in for evaluation.

People in the workshop asked, do you evaluate the group work?  Thing is, by evaluating the individual solution in this case, you are evaluating the group work!  If the students were effectively working together, communicating clearly with one another, pooling their talents well, then necessarily the product should be that each individual student can communicate by him or her self.  The student who held back from the group, who didn't actively participate, won't have the benefit of the four folks working together.  

This method does require that you assign lab exercises or problems that are beyond the simplistic.  AP-level questions are good here, or a simpler version of Kelly's group test-style lab practicals could work in this style.  If the whole approach to the problem is immediately obvious to more than one or two students in your class, there's little incentive for high level students to converse in stages 1 or 2.

I'll need to experiment to figure out the precise level of difficulty for this approach.  Nevertheless, I love the idea.  Let me know if/how it works for you.

24 July 2017

Ask for an answer LAST

Greetings from the American Association of Physics Teachers meeting in Cincinnati.  The exhibit hall opened last night with self-serve all-you-can-eat Skyline chili.  I have ascended to my eternal reward.

Since I arrived, I've done a wee bit more than eat chili and tour Great American Ballpark.  Yesterday I attended the High School Teacher Camp, organized by Kelly O'Shea and Martha Lietz.  We spent the day talking shop, meeting colleagues from around the country.  The keynote address was from Kathy Harper, discussing student perceptions of "mistakes" in physics class and how to channel those perceptions in a positive direction.

I've got a *lot* of notes on my phone which will inspire future posts.  For now, I'm going to relay an idea from Martha about her revised approach to AP Physics 1 justification problems.

I've written before about issues teaching students to articulate their reasoning on semi-quantitative or conceptual questions.  In sum: English class, history class, geometry class, and Fox News have taught students to begin arguments by picking a conclusion; then, to construct quasi-logical arguments twisting evidence to support that result, truth be danged.  Students are not used to the idea of beginning with the logical evidence, and then dispassionately asking what conclusion should be drawn from that evidence.

Of course, getting students even to articulate a quasi-logical chain of evidence is a tough challenge in physics class.  Come on, teacher, you know the answer, (think I) know the answer, if I'm right why do I need to say any more?  To break this first barrier, Martha had been an advocate of the "Claim-Evidence-Reasoning" approach to justifications.  For each problem, she would give space for the student's claim, i.e. their answer; for the student to write evidence from the problem statement or experiment; and then for the student to link the evidence to the claim through verbal and mathematical reasoning.  She required every student to address every element on every problem set.  

And it worked, sort of - Martha's students were willing to articulate their reasoning using words and equations.  Great.

But it was obvious to Martha that many students were merely guessing at the right answer, then cherry-picking evidence and reasoning that could support that original guess.  I've seen this intellectual stubbornness as well.  I don't know why people's brains have so much trouble adapting knowledge to new evidence.  I just know that they do.  Once a student decides that the answer is choice C, it takes an actual invasion by the Red Army to convince him that maybe the evidence points to choice D instead.

So, Martha suggested... why not ask for an answer LAST?

She subverted the paradigm to Evidence-Reasoning-Conclusion.  After the problem statement comes space for students to write evidence: facts, equations, and information relevant to the situation.  Then comes space for the reasoning: use logical connections to explain where the evidence points.  And finally, at the end, the conclusion: that is, the answer.  

Because the answer comes last, because students are not asked to commit to a conclusion before examining the evidence, students actually, well, examine the evidence.  They stop contorting their logic into pretzels to prove themselves right, and they start doing physics like a physicist.  Martha no longer has to suggest that their answers might be more likely to be correct if they'd use physics.

How am I using this?  I intend to rewrite some of my problem sets, especially in conceptual physics, making just one small change.  Problems have previously looked like this:

[Problem statement blah blah blah]



But I'm going to take a cue from Martha, and rewrite this way:

[Problem statement blah blah blah]



Let me know what thoughts you have, including whether this approach does or doesn't work for you.

20 July 2017

Mail Time: Detailed questions about the test correction process, especially in AP.

 Reader Jessica has some questions about test corrections.

1. For in class tests, you give half credit back for each problem missed. However, sometimes you do corrections with extra questions students have to answer in order to get the credit (which I think is a really great idea). Do all students have to answer these correction questions, or just the ones that got it wrong to begin with?

Just the ones they got wrong to begin with.  Since I’ve started teaching AP Physics 1, I often just hand back a blank copy of the test with a card saying which ones they missed -- this prevents the "well, if I just change this word here, would I be right?"

Is this change due to the way the AP 1 free response questions are asked to begin with? 

Yes.  On the old AP Physics B exam I used to ask additional questions in the style of AP 1 -- the idea is, you can't just get the number your friend got as an answer, you have to write out an explanation.  But AP 1 already asks for explanations.  So there's no additional work required, usually.

2. Do you tell the students what the correct final answers are when you give back the tests? 

No.  For multiple choice, they talk to each other and figure it out quickly.  That's fine, though, 'cause they have to TALK to each other, which is part of the point.  For free response, they figure it out too, but it's a more complicated process.

3. Do you do corrections on fundamentals quizzes? 

Generally no, because we do so many quizzes, and because fundamentals questions are straight-up recall.  For the end of year "Big Butt" fundamentals quiz, yes, we do corrections.

4. For your exam corrections (which I'm assuming are like midterm and final?), you said that you treat corrections like a separate 100 point test that students lose points from if they don't answer the corrections questions correctly (that's a tongue twister). Do all students have to do all the corrections questions even if they didn't miss the points for that question on the original exam? 

No, just the ones they missed.

6. For AP style tests with both mc and free response questions, do you have student fill out the multiple choice corrections form, or do you also ask extra questions for those on corrections? 

They just do the mc correction form.  If we're working in class, I'll often ask a question orally to be sure they understand subtle points.  And I read the correction carefully, to make sure they're addressing any misconceptions appropriately.

7. can you please explain how this works with the flow of the class... is this right?

Day 1 - take test  (Time to correct it and makeups of course) 

Day 2 - give back original test and blank for correcting, they work together to start on corrections. Collect back originals after a set amount of time in class.  Finish corrections for hw? 

Day 3 - collect corrections? 

That's pretty much right.  The schedule can change depending on other goings-on; for example, if half the class is on a field trip, the other half may do corrections, and field trip people just catch up for homework.  I'm very strict about regular homework deadlines, but I've often quietly allowed students who have a lot of corrections to do to take an extra day.  The goal is to get corrections right at all costs.

12 July 2017

Teaching AP Physics C to those who've already taken AP Physics 1: Sequencing

AP Physics 1 is designed as a first-time physics course.  While I suspect the majority of the 170,000 students taking the exam are seniors, the course is perfectly appropriate for sophomores or juniors; I even teach one section of 9th graders, and they do quite well.

So, then, what do you do when these underclassmen want to take more physics in future years?

I highly recommend AP Physics 2.  A high school student who does well in both AP Physics 1 and 2 could not be better prepared for college physics courses.  The deep conceptual underpinning provided by AP 1 and AP 2 will make even a calculus-based college course straightforward.  

That said, I know a lot of folks are teaching the calculus-based AP Physics C as a second year course.  Fantastic.  But it seems like a difficult transition: Much of the mechanics portion of Physics C covers the very same concepts mastered in Physics 1, though there's a good bit of calculus overlaid on those concepts.  Other than circuits, students have had zero exposure to electricity and magnetism.

Sequence AP Physics C like this:

September and October: Do algebra-based electricity and magnetism exactly as covered on the old AP Physics B exam.  Emphasize conceptual understanding.

November through mid-January: Go through the Physics C mechanics curriculum, paying primary attention to the calculus applications.

Mid-January through March: Start from scratch with the Physics C - E&M curriculum, reviewing material from the fall in context, and adding calculus applications.

April: Put it all together.

Why this sequence?

Electricity and magnetism are some of the most abstract concepts covered in first-year physics.  They're quite a change from Physics 1, where virtually every problem can be set up easily and quantitatively in the laboratory.  It's worth spending a significant amount of time just defining and using the concepts of electric field, electric potential, capacitors, magnetic field, induced EMF.  Using calculus while these ideas are introduced adds an unnecessary distraction.  Don't start with integrals and derivatives, which are conceptually opaque even to some of the best-performing high school math students.  

Start with the concept of the electric field, and the relationship F = qE.   Get students thoroughly comfortable with the direction of an electric force and field, with putting an electric force on a free-body diagram.  Then deal with electric potential and PE = qV.  Get students relating the existence and direction of an electric force to the difference in electric potential, and using electrical potential energy in energy bar charts.  Introduce capacitors as devices that store charge (according to q = CV) and block current.  Consider electric fields and potentials produced by parallel plates and point charges.  

Go on to magnetic fields and forces, first teaching F = qvB and F = ILB and their associated right-hand rule.  Consider how a current can produce a magnetic field.  Finally, explain induced EMF, and how to find the magnitude and direction of an induced current in a wire.

This is all AP Physics B stuff.  You can find a wealth of released exam questions on these topics, both free response and multiple choice.  Use them.

In about November, you can move on to mechanics.  You're at a significant advantage by waiting this long to start true Physics C material.  A number of your students will be taking calculus concurrently.  I used to have to teach them how to evaluate basic integrals, while my colleagues in the math department cringed and gnashed their teeth.  It's likely, though, that by November calculus classes have begun teaching integration, at least conceptually.  Physics can follow and reinforce calculus class, rather than the other way around.  And since your students are so well versed in mechanics concepts from their Physics 1 experience, they can focus on how calculus serves as a language expressing those concepts.

(Waiting until November for mechanics also solves a political problem.  If you start with mechanics, you give the impression that Physics C will be nothing but boring review, more of the same stuff from the first-year course.  Then when you bring on the electricity, you'll face a rather hostile audience who's already settled into a cozy senior year routine.  Start with the tough new stuff while your seniors are fresh and motivated.)

Finally, when you come back to electricity and magnetism, those concepts have had time to percolate in your students' brains.  Physics isn't mastered the first time students see it; it's mastered after the same ideas are seen in multiple contexts.  The full-on Physics C E&M unit doubly reinforces previous work: students revisit the concepts of field, potential, etc. that you introduced in the fall, but they also revisit the calculus language that you introduced with the mechanics unit.

I haven't had the opportunity to teach this course.  However, I've heard good reviews from those who have followed the approach I describe.  Try it.  Let me know how it goes.

04 July 2017

5 Steps to a 5 AP Physics: so many choices... here's a rundown.

Okay, obviously this post is a bit of advertising, but I've been asked enough questions that it's worth posting.  In early August, the 2018 versions of the 5 Steps to a 5: AP Physics 1 book will be published.

And I do mean "versions," plural.  It's hard enough that the College Board offers four different current AP Physics exams.  To add to the confusion, there are five different physics books under McGraw-Hill's 5 Steps imprint.  I wrote three of them.  I'd recommend four of them to you and your students.  Here's a rundown.

5 Steps to a 5: AP Physics 1, 2018 edition - by Greg Jacobs
This is the updated version of the top-selling AP Physics prep book that's been in print since the 2015 edition.  It includes two practice tests, both written by me, with complete explanations for all questions.  In the 2018 edition I've updated the text and fixed some errors.  Most importantly, I've rewritten one of the "about the exam" chapters to include the fact sheet that I use in my own class, and that my students carry around like a bible.  

5 Steps to a 5: AP Physics 1, "For the Elite Student" 2018 edition - by Greg Jacobs
I didn't come up with this title - McGraw-Hill marketing did.  I highly recommend it for your classes, though, because it contains some special and new material.  Jeff Steele - an AP Physics reader, head of the Virginia Instructors of Physics - has written a third practice test.

Most importantly, Jeff and I collaborated on a new section called "5 Minutes to a 5."  This includes 180 questions in the vein of TIPERS, but aligned to the AP Physics 1 exam, and all doable in five minutes each.  Each question could easily be the basis for an AP Physics 1 free response item, identical in style and physics content to the authentic exam.  These items would make excellent parts of homework assignments, or quizzes, or in-class worksheets to be followed up with experiments.  

5 Steps to a 5: AP Physics C, 2018 edition - by Greg Jacobs
This has been revised and updated.  The most important revision is that I rewrote some of the free response items in the practice exam to reflect the more intense use of calculus that we've seen over the past years.  In general, this is substantially similar to previous editions.

5 Steps to a 5: AP Physics 2 - by Chris Bruhn - not by me, but I recommend
I reviewed several of Chris's chapters.  He knows his business.  Some of the material is adapted from the out of print 5 Steps Physics B book that I wrote.  But it's Chris's book, and it is excellent.

Do NOT buy 500 Questions to Know by Test Day.
This monstrosity is under the 5 Steps imprint, so people think I wrote it.  I did not.  It is terrible.  It includes an enormous number of computational questions not even good enough for the old physics B exam.  I'm disappointed that this book exists.  I never had anything to do with it, I didn't even know it was coming out.  To me it is shameful that people have bought it expecting the same quality that the other books provide.  

But do buy the other four books, and even 5 Steps to a 5: AP Physics B.  
The out-of-print Physics B book is fantastic as preparation for a typical undergraduate course.  I'm trying to get McGraw-Hill to rebrand this book as a college physics prep book, because I still have alumni asking for it.  

Other questions?  Ask in the comment section, or by email.

29 June 2017

AP Physics 1 2016 problem 2 - bumps on an incline

The question in question asked about a cart on a long, bumpy track.  Specifically, it demanded a sample velocity-time graph for the cart as it crossed several bumps; then it asked what should happen to the cart's speed in between bumps if the angle of the track or the distance between bumps changed.  

I heard from and about a number of teachers who complained.  What kind of crazy-arse experiment is this?  No one does this in their class.  Ridiculous.  The AP Physics 1 exam has jumped the shark already.

My reaction to this question was, "Cool, what a great experiment, I wonder if I could set this up in the laboratory?"  And this week, Zach Widbin did set it up.  

Zach's teaching in Phoenix, but he's from New York, so he attended my summer institute in Mahopac, NY.  On the last day of the institute, teachers spend a couple of hours playing in lab, setting up experiments that they can share and use in their own classes.  

He inclined a PASCO two-meter track by two degrees.  He wrapped rubber bands around the track at 40 cm intervals, providing the bumps -- see the picture at the top.  The cart was a PASCO smart cart, which sends velocity-time data to an ipad via bluetooth.  The velocity-time graph is to the right.  

The original question asked what the graph should look like... but also, what should happen with a steeper incline?  With a larger space between bumps?

Well, Zach checked those things out, too.  The steeper incline gave a faster max speed.  He did smaller bump spacing, and got a smaller max speed.

The AP question itself postulated a very long track, with 100 bumps.  Zach only had a few bumps.  But there's no reason we couldn't tie together several of these two-meter tracks and try this again.  In fact, PASCO makes modular 50-cm plastic track pieces which can fit together in as long or short a string as you'd like.  Someone who has access to a wood shop (or, for those who prefer sexy terminology, a "maker space") could get a long plank, and then drill bumps into the surface.  Zach's approach isn't the only way to go - it's the one-morning-at-an-institute version.  I'd love to see pictures of your own setup.