Teaching Methods

Radical Renovations: The iOLab

I visited my alma mater today. The entirety of Green Street on campus is closed to traffic due to all of the construction. Buildings have gone down and come up and I half expected time to still be frozen in the year 1967 in the physics building.

When I walked in I found quite the opposite. Not only newly renovated rooms, but there is actually a women’s bathroom on the fourth floor. (This was always a running joke)

The reason I spent 6 hours in my car today, however, was to visit the Physics 101 class. iolab_remotes_redMy former adviser, Mats Selen, has been working on a new project: the iOLab. The concept is simple, it’s a multisensor system in a box. And it can do everything your $10,000 of Vernier equipment can do… for a little over $100. It connects wirelessly to your computer and runs with free, opensource software that does all of the analysis our expensive programs run.

On the other side of the coin, however, is a radical change in how the introductory level classes are being taught. When students walked into the lab, they had done a pre-lab experiment¬†earlier…..at home…..with their iOLabs. Quite simply, they made a stack of books, put another book on top by its edge and then looked to see how the force changed with the iOLab as it was placed at different distances from the book stack. Data were submitted ahead of time for credit. Students discussed the results at the beginning of the lab and then were given their task. It’s the classic peg-board demo, however, students had to find a way to relate the force to the placement of the probe if the pivot was located in the top corner.

This was the sum total of the direction given to students.

Within about 20 minutes all students were taking measurements. Some were looking only horizontally, others were looking both horizontally and vertically. Questions arose about the approach: if we change the angle at which we hold the probe the force will change. Are we supposed to do this with a horiztontal force too? I think that’s impossible.

They were told it’d be great if they came up with a mathematical relationship, but they’re just looking for the trends.

Within an hour students were plotting their data, recognizing it was an inverse relationship and running the curve.

One group really wanted to get the formula.

Another group recognized the torques should be equal and started calculating all of the torques. Percent uncertainty was one of the objectives focused on, so I wanted to see how well they were grasping that concept. I looked at the torques and noticed the values were .14, .14, .14, .15, .16. So I asked them how they were going to decide that those were constant and not increasing. They responded that they would have to determine their percent uncertainty and compare what was acceptable to those values.

Now, clearly there are major differences between high school junior and seniors and pre-med juniors and seniors, but at the same time, it was still remarkable how they were approaching the lab, developing their experiment and writing up their labs. It is something that very much excites me about the potential use in the high school classroom (and online classrooms, and college classrooms etc)

I also asked students about their previous physics experiences. About half reported they had taken physics in high school, ranging from regular level to AP Physics 1. ALL students reported that they felt they had a FAR BETTER grasp of physics now in this course, compared to their high school course. Several students who said this felt the need to insist they still had a great high school teacher ūüôā

The message, however, is clear: we need to give our students the opportunity to design and evaluate their experiments.

Also, the iOLab is a very exciting new piece of equipment. Morten Lundsgaard, currently the Coordinator of Physics Teacher Development
Instructor, is hoping to run workshops and/or a camp for high school teachers. If you are interested you should contact him!

Concept Modeling · Teaching Methods

Slicing a Cylinder for Moment of Inertia Integration

Guys….we’re in the throws of rotation. And at least one of my poor students has calculus immediately preceding¬†AP Physics C. I feel so bad for her. The day we started she had made up a calc quiz, came to day 1 of rotational inertia, then went to calculus. Oh did I feel her pain.

Arguably the most difficult part of deriving rotational inertia is the visualization of how to go about the integration. I mean, let’s be honest, once we find how to express dm the integration is¬†always an easy one.

Part of the problem is getting students to understand what it means to say things like dm, dV, dA, etc. They understand the definition linguistically, but it’s really hard to think of it practically. Tell them that dr^2 is zero and their minds are blown and bothered.

Day 1 of cylinders did not go well. Arguably, in part, because we were short on time. But also because the what why how was overwhelming.

I remembered a demo someone had shown where they 3D printed their objects to roll down the incline. They had actually made nesting cylinders, which then served as a great way to discuss integration.

I’m trying to think of a way to visualize¬†each of the d-steps of the cylinder integration for my students with materials I have on hand. As I’m digging through the closet I notice the slinky coil. It’s nearly perfect!!!

Ideally, I wish I had one with nice thick coils so we could take about the cylinder with R1 and R2, but this will suffice for the most challenging part.

So imagine you have a cylinder¬†of length L, and inner radius R1 and outer¬†radius¬†R2 and would like to determine the moment of inertia about its center…

IMG-2037 (1)

First, as always let’s define rho, but we have to find dm in terms of r. So how do we do that?

Well, let’s take some horizontal slices, where each slice is dm… now we can see that dm = rho*dV…but wait… what is dV?

Well, if we make those slices infinitely small…is there really a volume left?

IMG-2040

Ah! so dV is really dA, and we are looking at it across the length of the slinky, so dm = dA*L!

Conveniently, I know that A=pi*r^2, so dA = 2*pi*r dr

And the rest is substitution!

Teaching Methods

Pumpkin Projectiles

You can smash your Halloween pumpkins! Each year at our science center, Discovery Center Museum, they will launch your pumpkins (up to 8kg) with their 10 ft trebuchet which is loaded with 400 lbs. (Why they limit by kg, but load with lb, I have no idea)

As a last minute thought, I blasted a text to my students: determine the initial launch velocity of the pumpkins. Double the points if you confirm the presence or absence of air resistance. Present in claim, evidence reasoning form. Have it ready for Monday.

Naturally, I couldn’t let my kids have all the fun (or the answers) so we went together as well. The pumpkins go way too fast/far/high to collect enough data at 60 fps, so I filmed in slo-mo (here is the original video), tracked the pumpkins on Vernier’s Video Physics app…

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Of course, I had to see the graphs right away…oh so pretty…

then loaded the spreadsheet into excel and adjusted the times for the slow-mo camera. Additionally, since I had been given the specs in feet, I had to convert the units to meters. (I used the length of the base of the trebuchet to set the scale).

 

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Can we just discuss the beauty of these regressions? The vertical velocity is broken into three parts: the launching, from release to peak, and from peak to ground. You can see how quickly air resistance comes into play. The weird fall off tail is where the iphone goes back to 60 fps in the last moments of the video

 

Oh how beautiful thou art, quadratic functions! Yes, air resistance¬†is a factor, slowing the acceleration to about 3 m/s/s. There’s also a horizontal acceleration of about 1 m/s/s as well. Launch speed worked out in the ballpark of 12 m/s.

My kids who went are still crunching their numbers…we’ll see what they can produce!

 

Food

Shameless Cookbook Plug

In addition to being a physics teacher  momma, I am also a clergy wife.

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My husband’s ordination to the priesthood, September 1st, 2013

One of the needs I noticed within our community was a desire to learn about how our tradition of fasting is supposed to look in the practical lifestyle of an Orthodox Christian.

The cannons call for a strictly vegan diet during the fasting seasons, which include 40 days before Easter, 40 days before Christmas, 2 weeks in August, every Wednesday and Friday, and a few other special days during the year.

So I wrote this cookbook:Screen Shot 2017-11-05 at 9.14.27 PM

All of the recipes¬†are simple and vegan, with an introduction to Orthodox fasting spirituality. We start our Nativity fast in 10 days, so it’s ordering time!

Family

Magic School Bus Reboot: My Take

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Last night I introduced my son to Magic School Bus. The real version. The one I grew up with. The one I realized I still have all of S1E1 memorized. (It’s the one where they visit all *nine* planets) There were a lot of things I realized about the original looking back as an adult/teacher/parent. First of all: no one considered the consequences of having Arnold march toward the “camera” and the camera is at¬†crotch level? Secondly: I appreciate¬†the immense diversity included back in the late ’90s. All of the kids are smart, and the different background characters are actually played by voice actors within those respective backgrounds. Third: The show shared information. In a very jam-packed manner. And in a manner where the students would make an observation and either fit it with a model and come to a conclusion (intestinal ville are like sponges!) or pose a question that Ms. Frizzle or another student would answer.¬† It was based on a field trip and so each episode is like a museum exhibit on magic, but in a very “hands on” sense.

The remake, however, seems to be trying too hard at its mission of “integrating technology”. The Netflix Revival Series, “Magic School Bus Rides Again” is produced by Stuart Stone, who most of us know as the original “Ralphie” from the 1990’s series. First of all, I get the idea that this series wasn’t made for me. But they clearly intended to cater to us now parent-aged fans: Ms. Frizzle (the real one) is still there, with Lily Tomlin reprising her role. The original gang is just a few grades ahead. Our favorite lizard, Liz, is still a part of the classroom. The opening sequence is identical, but with Lin Manuel Miranda putting his own twist on the meter of the music.

And then there was the first episode: Miss Frizzle of the Future.

Now, I must preface this with something related to my work-life. Our Creative and Performing Arts Academy has their fall musical this weekend. The show is Little Shop of Horrors. Audrey II has literally taken over the school.audreyii

Now, being the sheltered individual I was/still am and since Little Shop of Horrors was just slightly before my time, I was unaware of anything about the musical or film until this weekend.

So I’m sitting down to check out the new Magic School bus and what happens?

The New Ms. Frizzle brings in her very special magical plant.

And the plant is Audrey II.

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Yea Arnold, I’m right with you on that one

So the kids go on their field trip to the Galapagos Islands. DA has an ipad¬†in place of her books and the kids wear special goggles that trace out food hierarchies. It’s like tech integration for the sake of tech integration…which is definitely¬†not best practice. Like, “hey kids, let’s wear these $100 goggles which will let you see ONE thing! Ok, we don’t need them ever again!” yea, no thanks.

Meanwhile, Arnold, in an attempt to foil the new Frizzle, dumps Audrey II on the Galapagos.

Well… we all know how that is going to go…

Yea…

So the theme of the episode was invasive species. Arnold goes into the future and learns that the plant has taken over the whole island. They tried to tame it with bunnies, but the bunnies took over too.

Meanwhile, I keep waiting for the plant to speak…

So Arnold goes back to the past to stop the plant from taking over…but it still breaks through the pot. The new girl, we shall call her Audrey, drop kids Audrey II.

Fortunately, she is NOT mortally wounded and does not feed herself to the plant, neither does Arnold run into it with a machete, rather the whole class kicks in to wrangle it

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Ms. Frizzle saves the day, and at the end of the episode I’m like

what

just

happened.

I wasn’t able to make it to my school’s production of Little Shop of Horrors, but apparently, it didn’t matter. I got the Magic School Bus Invasive Species Episode instead.

Needless to say, I wasn’t really impressed. I think the show tried too hard making us empathize with Arnold that, “hey kid, things are changing, and this show is going to be different” The majority of the complaints about the revival are related to the “cheap” animation and the apparent lack of creativity/weirdness of the new Ms. Frizzle, but I’m going to argue that if we can look past the superficial stuff, this revival has deeper, fundamental problems.

I recognize that generations change and we, as teachers, learn to adapt to that change, but I have a really difficult time lowering standards because “times are a-changing”. What do I mean by that? That somehow nothing is interesting if it’s not sensational. If the characters aren’t yelling at each other or at a situation that the show is boring. That this show needed to trade close, careful observation by its characters (hey, what’s that?) for sensationalism (oh my god, the plant is everywhere…and so are the bunnies). If the original show demonstrated to kids how to be scientists, the revival is demonstrating that cool gadgets are the only way to really see the world.

Maybe the other episodes are better, but my guess is given the rapid production of these Netflix reboots, there’s not much change to be anticipated.

Update 11/6: I stand corrected. Perhaps it was just the irony of the weekend. I watched the magnetism episode tonight and it was¬†excellent. Like.. so much so I’m considering using it in my regular physics class in the spring. Explaining magnetic domains is¬†so hard because it’s not tangible¬†at all. I was really impressed. Granted, I still feel like the volume of science content just isn’t quite at the same level, but I certainly appriciate tacking such difficult concepts!

In My Class Today

Flying a Plane with a Falling Bathtub

It’s 2014…I’m teaching 5 sections of Earth Science and visiting my parents. They have PBS on and we’re in the middle of this documentary about World War II. Except it’s not quite that, it’s actually about one of the escape attempts from Colditz Castle: the place where any POW was sent if they had attempted to escape the German prisons.

Now just imagine that for a moment.

It takes a special kind of person to plan, execute and attempt an escape. You need to be creative, clever and bold. ::cough::gifted kid::cough my students relate strongly.

And then the Germans think it’s a good idea to put all of these brilliant, audacious minds in one place.

So one of the prisoners gets this idea: let’s build a glider out of the stuff laying around the castle and launch it off the roof by attaching it to a bathtub. It’s a crazy idea, and it’s a perfect two-body physics problem, and I’m going crazy that I can’t show this movie to my students right now.

 

Originalglider
The original glider from 1945

 

Now I teach a full load of physics and it is an annual treat in my introductory course. First, I have my students decide what types of things will need to be taken into consideration. The questions fly: where did they get a bathtub? Where did they get concrete? How did no one see them? They actually built the glider?

Then I have them do the two-body problem. I have had them calculate whether the original specs would have allowed the plane to fly, and also had them calculate the drag force from the test run on the model Professor Hunt riggs up when they need 1.1g.

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The students get an incredible history lesson, and get to see the physics they just learned in legit action. I always pause the video when Professor Hunt is rambling off how he analyzed the data to determine the plane’s acceleration and ask my students if they caught it all. Then we go back to the video of the launch. LOOK! There are distances marked on the runway! We discuss how Professor Hunt would have determined the acceleration. How plotting d vs t is the best option. How we’ve been doing precisely that with the motion detectors in our recent pulley labs.

My first year doing this I split the film up over the course of three days. On the final day I asked my students to write reflective letters to Professor Hunt.

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Professor Hunt actually obliged and wrote personal letters to each of the students!

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I think it’s an amazing story and my students get a lot out of it each year. When I set the video up for 7th hour after AP Physics C one of my students said to another, “oh look what they’re watching today! I love that movie!”