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September 5, 2015

Why Lab Journals?

Since I teach AP Physics (two varieties of it, in fact), my students are required to keep a lab portfolio.   In past years, I have required that they keep all their labs in a three-ring binder that served as their portfolio. This year I made a change. I decided to require the students to keep a lab journal in a graph-paper composition notebook.

I made the change for several reasons, but one of them is predominant: I want to assure that the student's work is his or her own work. Last year, four well-meaning girls subdivided the task of preparing the lab report, printed four copies of a beautiful lab and handed it in, each copy with a different girl's name on it. I had to explain to them that this was not acceptable. But I had a hard time justifying why. When scientists work in a group preparing a report, we don't each prepare our own report and then compare: we work together and put all our names on the paper and submit one paper.   But the purpose of those papers is not the author's learning, it's the sharing of information. The purpose of labs in a physics classroom should be to enhance the students' learning and understanding of the content. For that purpose, each student needs to complete his or her own report.

So in order to further the student's learning, I require the students each to keep a lab journal which they must bring to class on lab days. I got the idea from Connie Wells, a physics teacher in Kansas City, but it took me a year to warm up to it. After all, it means periodically either (a) staying the weekend at school to grade or (b) lugging 70+ journals home for the weekend. Ultimately, I decided it was important to make sure each student went through the thinking process involved in creating a lab report, and to do that, they each need to write the report by hand. I know that seems "old school" but recent studies have shown that taking notes by hand is more effective than taking notes on a laptop. Perhaps the same is true of lab reports. If they are writing out the procedure by hand, then I know they are at least thinking about it for the short time they are writing.  

I'm not a Luddite, and I am not opposed to electronic lab portfolios.  I'm just concerned that if a student copies and pastes the procedure or conclusion from another student, then they are not learning about writing a procedure or conclusion.   This was happening all too frequently when I collected labs on loose-leaf paper.  Students asked if they could "type the labs" and I said "sure." After all, that avoids the problem of reading bad handwriting.  But this led to the situation above, with four well-meaning, intelligent girls co-authoring a single lab. Students have already used Tracker to collect data from video analysis, used Excel or Google spreadsheets to create graphs with best fit lines, and worked with motion detectors. They can work together to collect data, and print the data table to be glued into the journal later. They can work together to create graphs on spreadsheets, which can then be added to the lab journal.  But the calculations, error analysis and conclusions, arguably the most important parts of the report, must be done individually and hand-written in the journal.

Not all laboratory activities are written up in the lab journal. Only the ones that merit a complete lab report with purpose, apparatus, procedure, data, calculations, error analysis and conclusion go in the journal. So far we had some neat motion detector activities that don't require a full report.  I don't collect the journals after every lab since I am grading them in a pseudo-standards-based-grading manner (more about that in a future blog post), but also because the journals need to be with the students in the lab while they are working, not with me waiting to be graded.  It requires planning, and a cart to carry the lab books around, but so far, I'm pleased.  There are lots of details to work out while implementing a new procedure in a course, and I'm sure I'll change the requirements frequently as I go along (that's why Google Docs are great) to better meet the students' needs. I hope to learn a lot through this process.

February 24, 2015

Using Google Docs for Inquiry Based Labs

I confess: I love Google Docs!  And the more I use them, the more I love them. First, Google Docs save paper. Second, they allow me to procrastinate…I mean…develop in-class activities spontaneously as I see the need. Third, they save me lots of trips to the copy machine.

But in all seriousness…. I create a document for the students and post it to the Google Drive folder I share with them that has class handouts and solution pages. I use Google Docs for the weekly schedule, and I link the assignments and in-class activities to the schedule. If the schedule changes (e.g. we have a snow day), then I can change the Google Doc and not have to print new copies. The students also have access to the schedule 24/7 wherever they have their smartphones. Some students like to have a paper copy of labs to read and remind them of what is required, and these students can print out a copy for themselves. Some students don't need this, don't want it and would just lose it as soon as I gave it to them.

My most recent discovery is using them for inquiry-based labs. For guided-inquiry labs, I like to initially give the students very few instructions. I usually just provide a list of equipment and a guiding question. Perhaps I include a diagram if it is relevant. For the most recent rotational inertia lab, I started by posting a Google Doc that listed the task. I asked them to design a method to make measurements that would allow them to calculate the moment of inertia of a spinning T-shaped PVC apparatus (based on Connie Wells' design).  I let the students work for a double period (89 minutes) and they all came up with ways to make measurements and calculate the torque on the rod and the angular acceleration. But they all only made one measurement. They performed several trials, but they used one hanging mass to provide one torque to cause one angular acceleration.

So the second day when we met we talked about the fact that we could get a more reliable value if we used a graph to calculate the moment of inertia. We decided to plot torque versus angular acceleration, slope of which is the moment of inertia. So as soon as we decided that, I unveiled the new version of the lab in the Google Doc, with the additions and changes to the requirements in red. It took them only one period (42 minutes) to make the remaining measurements. The students opened up a Google spreadsheet, shared the file among the members of their lab group, and entered all their data so that all students in the group had access to it.

I didn't want to start the lab by telling them to plot a graph: I just wanted them to focus on what to measure and how to measure it. So I left the graph requirement off the lab to start. Once they knew how to make one set of measurements, then they were ready to make a graph. The Google document is flexible the way a paper handout is not. I can also change the analysis questions they are required to answer based on class discussions or observations of their group work.

The dynamic nature of a Google document makes it ideal for inquiry, when I don't want to give away too much of the procedure initially, but want to end up with a complete document in the end, stating the requirements of the lab. The document can evolve as the lab work evolves.

February 13, 2015


I've made a small attempt to flip my classroom this year. I believe that when the students are in the room together (and with me), they should be interacting with me and with each other. So when I want to introduce the students to a new concept, or develop some ideas, equations, etc. that we discovered during inquiry in lab, I assign them to watch a video. Then the next day we use TIPERs or traditional practice problems to apply what they learned in the video. I don't have time to create every video that I need them to watch so I am grateful to those who have already created high-quality videos. I have been a fan of Dan Fullerton's APlusPhysics videos since I discovered them early this year. Recently a student discovered some other videos on her own and sent me the link in a message.

These physics lessons can be found at and they are made by a high school teacher from Maryland named Yau-Jong Twu.  I've only had time to look at a few of the videos, but I was impressed by what I saw. Ms. Twu writes incredibly neatly on a piece of paper and uses a yellow pencil to direct the viewers' attention. Unlike my videos, which are usually made in haste in one 10-minute take, hers have good production value. She has a nice title in the beginning and suggestions for when the viewer can pause the video to make his or her own calculation.  She draws images and diagrams using a ruler and a protractor.  And she occasionally uses props to help illustrate her point.  In the video entitled "Angular Momentum and Angular Momentum of a Point Mass," she uses two small Lego people to demonstrate how an object moving in a straight line has angular momentum.
She shows how the Lego person in the white hat has to turn his head to follow the moving Lego person in the black hat.  Thus, the moving Lego person has angular motion relative to the stationary person, and thus angular momentum relative to him.  Genius!  I never thought to describe it that way before*. She continues to derive an expression for the angular momentum of an object moving in a straight line, and does so in a very clear, coherent way.
Many of her videos involve ranking tasks, or other conceptual questions.  Another one of my favorites is titled "Spheres Going Up Inclines with Different Friction." Two spheres are rolling without slipping toward two different hills.  One hill has friction, one does not. She asks the viewer to predict which sphere will go higher up the hill. She pauses for 8 seconds, displaying a prompt for the viewer to stop the video if he or she needs more time to think.
Ms. Twu then continues to explain the physics. This is exactly the type of comparison task (found in the TIPERs books**) that elicits conceptual reasoning and fosters deep conceptual understanding.  

I've only just discovered these videos, but I plan to post various individual videos to each unit web page for the students to use either to develop concepts, or simply for review if they need it.  And I plan to post a link to so students can search out her videos for any topic they need. 

And the student who discovered these got a free "Late Homework Coupon" for her efforts.   

*Perhaps I shouldn't admit that, given that I have been teaching angular momentum for 25 years.  So I'll blame it on the fact that I don't have children, and thus do not have extensive experience with Lego people.
**Links to sources for the TIPERs books can be found on my Teacher Training Site, on the "Book Resources" page.  

February 6, 2015

Using Direct Measurement Videos to Teach Rotation

I'd like to share with you a tool I've just fallen in love with: Direct Measurement Videos.  These videos are produced by the Science Education Resource Project (SERC) at Carleton College by Peter Bohacek, Matthew Vonk, Ellen Iverson and Karin Kirk. The videos are short, high-quality, slow-motion videos of real events. The videos have scales drawn on them so students can measure distances and angles. They also have a frame counter so students can use them to measure time.  Other data is provided as needed.

I heard of these videos probably over a year ago, but as with most things I encounter at AAPT or other professional development, repeated exposure is required before I am ready to adopt it and use it in my classroom. I believe that hands-on labs are the best types of labs, and I believe that video analysis is a wonderful way to make measurements of all kinds of motion, particularly motion in two dimensions.  But sometimes the content doesn't lend itself well to hands-on labs: universal gravitation is one topic that comes to mind. For this type of content, simulations can be helpful. Direct measurement videos can serve as an additional lab after a hands-on lab; they can be used to lead a class discussion; and they can be used as homework. Using these videos as an alternative to the traditional book problems encourages deep conceptual understanding as it requires the students to decide what to measure to answer the question, rather than just using the numbers they are given. I have used them for all three purposes in the rotation unit alone.

I started the rotation unit with a DMV homework assignment related to measuring and calculating angular velocity and acceleration.   Then we did a hands-on lab about rotational energy using soup cans, and another hands-on lab about torque using a T-shaped device made with PVC (based on Connie Wells' apparatus). After those were completed, we used DMVs to study angular momentum.   This time I gave them an activity that started as "lab" in groups in class, and was to be completed at home. They made measurements on a video of a disk-on-disk collision, verifying that angular momentum was conserved, and that kinetic energy was lost to thermal energy via friction. They also made measurements on a video of a rocket accelerating a disk. And finally, I used the "Marble and Block" collision to lead a discussion of a collision in which both linear momentum and angular momentum are conserved.

When you get a chance, take a look at these videos. Many of them come with activities already prepared. And it doesn't take long create your own assignments for students based on these videos. Good luck and have fun creating!

January 13, 2015

Another leak in the pipeline...

Today, a student came back to Niles West to visit.  He took AP Physics C and got a 4 on the Mechanics portion of the exam.  He liked physics and thought about majoring in physics.  I think I remember him saying he took chemistry and calculus his freshman year, and didn't love it, but hung in there.  He remembered liking AP Physics C in high school, so he decided to major in physics and signed up for Physics 211 at U of I.  He said it was SOOOO hard, he hated it and it was the first C he got in college.  And he also was miserable in his Calc 2 class.   So he's changing majors.  No more physics.  

He's a bright young man.  I don't remember the grades he got in my class, probably B's both semesters.   And that's not easy.   I can think of several students who claimed to want to go into engineering, but, in my opinion, didn't have the work ethic or problem solving skill to manage it.  This student is not in that category.

I wish I could say that he is the first of my students to enter college loving physics, having taking AP Physics C with me, only to be driven away from it by an overly difficult freshman physics course.   I know of at least two: one at Princeton, and the other one at U of I.  And who knows how many of them are afraid to tell me: how many students have the nerve to tell their physics teacher they no longer like physics?

It makes me sad.  It makes me angry.   The nation decries the lack of STEM majors, and makes a push to increase STEM courses for high school students. But then when they get to college, droves of students are driven away by large weed-out courses.   Maybe you can claim they didn't like it ENOUGH, and maybe that's true.   Or maybe there is something wrong with some of the college physics courses out there, and something wrong with the concept of a "weed-out" class.  Perhaps we are pulling some of the good fruit-bearing plants out with the weeds because our courses are too hard.

I don't mean to imply everyone has to like physics.   I personally "leaked" out of the "pipeline" when I had to learn quark wave functions in grad school.  

I asked him to send me links to the past tests they publish on line for students.  Perhaps that will give me some more answers.   But for now, it's a mystery to me.  Would he still be in physics if he had taken it at a less prestigious college or university (as Malcolm Gladwell posits in David and Goliath)?  Who knows?  In any case, the U.S. lost another STEM major this past semester.