Near-Space Balloon

1 Reply

The Physics Club at my school recently completed our second-annual near-space balloon launch and recovery. Our goal was to launch the balloon payload to over 100,000 feet. We planned to record pressure, temperature, and radiation data; test the effects of altitude on biological samples; capture photos and video; and, ideally, recover the payload! While we didn’t achieve every goal, the launch and recovery was a resounding success.

An alumni of the Physics Club worked with Ken Walczak from the [Far Horizons project](http://www.adlerplanetarium.org/investigate/participate/farhorizons/?searchterm=horizons) at [Adler Planetarium](http://www.adlerplanetarium.org/) last summer and suggested that we contact Ken. The students contacted and met with Ken on their own, set the goals for the project, and designed and constructed almost every element of the balloon. (Ken provided the pressure and radiation sensors, while I provided the Arduino and temperature data logger.)

This project was a good excuse for me to buy a new Arduio Uno and the [Data Logger shield from Adafruit](http://www.adafruit.com/products/243). The data logger shield was easy to assemble, simple to interface with via the Arduino, and convenient to retrieve the data due to the SD card storage.

Armed with our supplies, we met up with Ken in El Paso, Illinois (selected due to its launch-friendly park and sufficient distance from Lake Michigan). With his experience, Ken provided many tips as well as the 1000-gram balloon!

We inflated the balloon:

IMG 5196

… assembled the payload and connected it to the parachute and balloon:

IMG 5201

.. and the president of Physics Club let go! (That process took over two hours!)

100 0316

The camera captured a great arial view of El Paso, Illinois:

IMG 1477

… and quickly rose above the clouds:

IMG 1567

While not definitive, based on our data, we estimate that the payload reached at least 105,000 feet:

IMG 2109

… before the balloon popped and the payload fell to earth:

IMG 2325

We used a cell phone that sent GPS coordinate to a web site to track the balloon. Unfortunately, the cell phone stopped sending coordinates immediately after launch. As a result, we had no idea where the balloon was until the payload landed back on the ground, two hours and forty minutes after launch. Fortunately, it landed in a vacant lot in a subdivision relatively close to the predicated location. We were able to retrieve the payload, recover all the data, and be home for dinner.

We had some issues with the data logging. The pressure data wasn’t valid (we were having issues before even launching; so, we weren’t too surprised). Also, the Arduino got too cold when falling and some of our temperature data may be suspect. Regardless, the graphs of temperature vs. time correlated with radiation counts will provide some authentic data for our freshman earth science class next year:

BalloonData

Next year, we plan on replacing our cell phone-GPS tracking system with a GPS receiver connected to a APRS transmitter. We don’t like losing contact with the payload during launch. We also hope to invite our district’s middle schools to design experiments to include in the payload. The students also expressed interest in adding a camera facing upward to capture a new perspective.

If you are interested in launching your own near-space balloon, feel free to contact me and, while limited, I’ll share our experiences!

Holography

1 Reply

There is a long tradition at my school of students creating holograms as a final activity in physics. Everyone gets to make their own and keep it. I have heard several alumni mention that they still have their hologram. Just this week, an alumni who is also a dean remarked that he still has his hologram from 20 years ago. Sometimes the purpose of an activity is learning; sometimes, just to inspire. This is the later.

I’m not sure how we first made holograms, but at some point in the distant past, now retired teachers must have attended a holography workshop led by Dr. Jeong from Lake Forest College. A couple of summers ago, I attended a Chicago Section AAPT meeting and was surprised to learn that Dr. Jeong was leading the workshop!

For years we have been making [reflection holograms](http://www.integraf.com/a-simple_holography.htm). These usually turn out well. The disadvantage is that there isn’t much depth and, therefore, the 3-D effect isn’t as dramatic. The advantage is that reflection holograms are easily visible in white light (sun light is especially effective).

Last year, after attending Dr. Jeong’s workshop, we decided to try and also make [transmission holograms](http://www.integraf.com/a-make_transmission_hologram.htm). Dr. Jeong actually demonstrated how to make an “omnigram” which is a combination of a reflection hologram and a transmission hologram on a single slide. We tried this, but only the transmission holograms were visible. The transmission holograms were amazing. They have an incredible depth which allows larger objects (or a collection of small objects) to be captured. The disadvantage is that a laser is required to view the hologram (a green laser pointer works better than a red one).

This year, we provided students an option to make either type of hologram. They split about 50-50. As the price of laser pointers continue to fall, we may soon only make transmission holograms.

We order all of our supplies from [Integraf](http://www.integraf.com/). We use the PFG-03M holography slides, the JD-4 processing kit, and the DL-4B laser diode. The setup for transmission holograms is relatively simple. I have detailed photos of the slide holder (on the left) and laser (on the right). The objects are positioned between the slide holder and laser. In the back, is the shutter which blocks the laser light and consists of foam board covered with black felt with a base of two large binder clips.

holography setup

I built the slide holder from a 2.5″ picture frame. The picture frame is painted a flat black. Black backing material is glued to the top of the picture frame to ensure that laser light does not enter the sides of the slide. The picture frame is secured to a base which is a tea tin filled with sand and covered with black felt. The picture frame backing is slid behind the slide in the frame to secure the slide (emulsion side faces the scene).

slide holder

The diode laser is secured by a clothespin in a tea cup filled with sand. It is is positioned on a base which consists of three physics texts covered with black fabric. I added a switch and a two-pin connector to the battery box which results in a more reliable connection and easier operation.

laser

If you are interested in making your own holograms, feel free to contact me and I’ll try to answer any questions that you may have. Dr. Jeong is very approachable and provided several tips based on questions that I posed.

**Update**

I realized that it would be helpful to show some examples of these holograms. It was challenging to photograph them, but here is my best attempt for a transmission hologram:

transmission hologram

And here is a reflection hologram:

reflection hologram

Nuclear Physics Project

2 Replies

This year, after completing our four major units of second semester in regular physics, we planned on a project that would address Illinois Science Goal 13: “Understand the relationships among science, technology and society in historical and contemporary contexts.” This project has the potential to move beyond content and integrate perspectives from many other disciplines. I had some ideas in mind, but after the Fukushima disaster, my colleague and I decided that our final project would focus on nuclear physics. Here is the description of the project that we will distribute to students:

Download (PDF, 51KB)

One aspect of this project that I’m really excited about is that we will be publishing all of the projects on Wikispaces so that they can be viewed by other students and professional both within and outside of our school.

I’m also very excited about the manner in which students will present their projects online. In order to highlight how technology influences the communication of scientific ideas and events throughout our society and how that has changed throughout history, we’ve encouraged students to create a juxtaposition between the time period of the topic and the presentation method that they select. For example, if their topic is historical, choose a presentation method that is modern (e.g., Marie Curie and her Facebook status updates). Or, if their topic is modern, choose a presentation method that is historical (e.g., black-and-white news documentary of fusion reactor).

I’m very interested in your feedback or involvement. Do you know of other topics related to nuclear physics that we should add to our potential topics list? Do you have ideas for other engaging presentation methods? Are you or your students interested in viewing and commenting on these projects in late May? If so, please contact me either via Twitter (@gcschmit) or via e-mail (geoff at this domain). Regardless, when the projects are published, I’ll post the link here.

**Update: 20/6/11 11:09 PM**

All of the student projects are on [nnhsphysics](http://nnhsphysics.wikispaces.com/) wiki hosted by [Wikispaces](http://wikispaces.com/). I created an [index of sample projects](http://nnhsphysics.wikispaces.com/Sample+Projects) which contains projects on a variety of topics created in a variety of mediums.

Circuit Sudoku

4 Replies

During this semester, which mostly consists of electricity and magnetism, I’ve really started to appreciate that the content is the vehicle through which students develop problem solving, critical thinking, and long-chains of reasoning. Later I will write how electrostatics is a great start to developing these long-chains of reasoning before we really exercise that skill with circuits. While not as challenging, circuit analysis is a good application of problem solving skills that illustrates how organizing data can make it much easier to solve problems.

We’ve started calling this problem-solving approach Circuit Sodoku.

The technique has evolved over the years based on input by teachers and students. I expect that it is similar to techniques used elsewhere. Regardless, my students find it very helpful when analyzing complex circuits.

At the heart of the technique is the V = IR table which has the following elements described below and illustrated in the photo of a group’s whiteboard:
* three columns: V (voltage), I (current), and R (resistance)
* the first row represents the equivalent circuit which specifies the voltage of the source, the current through the source, and the equivalent resistance of the circuit.
* each subsequent row corresponds to a resistor in the circuit

Students follow these steps to analyze circuits:
1. solve for the equivalent resistance (redrawing the circuit after each step, if necessary)
2. calculate the current through the supply based on the supply’s voltage and equivalent resistance
3. look for resistors in series or parallel with the source and update the table with the current or voltage associated with that resistor
4. apply the loop rule and junction rule to complete blanks in the table

Whenever two of the three columns for a row are completed, students use Ohm’s Law to calculate the third value.

Here’s an example:

circuit whiteboard

Just to be clear, Circuit Sodoku is not the heart of our circuits unit. Before we start analyzing circuits in this manner, we have spent weeks developing our conceptual understanding of circuits using the [CASTLE curriculum](http://www.pasco.com/featured-products/castle/page_3.cfm). Many students find Circuit Sodoku a welcome break at the end of the unit.

Circuit Sodoku used to be the most challenging problem-solving application of my circuit unit. Now it is the easiest. I’m pleased we are focusing more on developing these essential problem solving, critical thinking, and long-chains of reasoning skills.

Circuits Lab Practicum

2 Replies

This year, we created a new lab practicum for the circuits unit. In addition to the traditional activities of having students draw a circuit diagram from a written description, build the circuit, and measure the voltage across and current through a specified resistor; students had to infer the circuit diagram for a collection of lightbulbs based on their observations.

This activity was inspired by an old Science Olympiad circuits event. As shown in the following photo (which is somewhat hard to discern due to the pattern of the fabric), four labeled light bulbs protrude through holes in the fabric. The fabric hides the wires connecting these light bulbs. Students turn on the power and then make observations by unscrewing and screwing in the light bulbs. Based on their observations, they draw the circuit diagram and justify their conclusion.

circuit lab practicum

Students were most engaged in this activity of the lab practicum compared to the others. I think the fact that it was a unique way for them to apply their knowledge and inference abilities made it so interesting. It also had the unexpected benefit of reinforcing the idea that physical order of the light bulbs has no effect on their brightness. That is, the first light bulb in series from the positive terminal of a battery is not the brightest because it is “first.” Several students commented that there were several circuit diagrams that they could draw that would match their observations. It was reassuring that they came to this conclusion!

Einstein Day

1 Reply

Last week, I got fed up and couldn’t take it anymore.

I’m fortunate that many of my students are really curious about science and ask fantastic questions.

Sometimes these questions are directly related to the topic that we are investigating, and we discuss them immediately.

Sometimes these questions are unrelated to the topic at hand but are of a limited scope and can be discussed and as a short tangent to the “plan” for the day.

Sometimes these questions are directly related to a topic that we will study in the future, and we table them until that time.

Sometimes these questions are unrelated to anything we study, are not quickly discussed, and are fantastically engaging. Often these questions are in the area of modern physics. Since we don’t study anything in my regular or honors physics courses that was discovered within the last century, these topics are not part of the curriculum. (Yes, I’m working to address this.) An answer of, “we study that in Advanced Physics” is unsatisfying since most of my students won’t take a third semester of physics. Our curriculum, especially in honors physics, is so aggressive that we really don’t have the flexibility to chase down these fantastic tangents.

So, last week, while discussing the doppler effect in the context of sound, a student asked what would happen if a car traveling at the speed of light turned on its headlights? Would the doppler effect apply in some way? Wow. The other students were immediately engaged and started proposing ideas and more questions. I couldn’t bring myself to once again say, “we study that in Advanced Physics.” Instead, I got a huge sticky note, slapped it on the wall, titled it, “Physics Questions,” and added the question. I declared that we would capture fantastic questions like this and dedicate time later in the semester to have a series of short presentations and discussions to explore them. Students can research questions in which they are interested and I’ll take a few too.

They asked when we would do this. I Googled for Einstein’s birthday. March 14th. Someone remarked, “hey, that’s pi day!” Serendipity.

Anyone care to join us?

How My iPad Replaced My Laptop

3 Replies

I started the fall semester with the intention to see if my iPad could replace my laptop during the school day. In short, it has. How was this possible? Before I elaborate, I want to be clear that I have an iMac at home that I use all the time and there are days that I use my school-issued tablet due to limitations of the iPad.

Key Features
============

I’ve been surprised by several of the features that I most appreciate about the iPad.

The best is that it turns on instantly. It takes my school-issued tablet several minutes to boot. Even if I wake it from sleep, it fails to connect the the wireless as often as not and requires at least a reboot. While this is an appreciated feature for me, I’ve recently realized that this is a killer feature for iPads in the classroom. When a student pulls a laptop out of the cart, boots it, logs in, and then later, shuts it down, a substantial fraction of class is spent with these worthless tasks.

The iPad battery is fantastic. I never charge it at school; I just plug it in every night. My bag is light and now there’s more room for lab reports.

VGA output is a critical feature. I need to display a variety of media via an LCD projector in my classroom. VGA output is not a universal feature; it has to be supported by individual applications. I’m surprised by how many people are unaware that an iPad can project slides via an LCD projector.

Key Applications
================

I rely on a number of important applications on the iPad in order for it to replace my laptop. Just as importantly, I rely on a number of applications on my Mac that interface with my iPad.

Omnifocus
———

My life is manageable because of Omnifocus. I’ve followed the Getting Things Done methodology or something similar for years and Omnifocus; which is synchronized between my Mac, iPhone, and iPad; is the best implementation of it. Without Omnifocus, the iPad wouldn’t even be an option.

Yojimbo
——-

Yojimbo is my digital junk drawer. All of my bookmarks, notes, receipts, etc. are stored and tagged in Yojimbo. I don’t often need to create new items on my iPad but I definitely need to search and access them.

Keynote
——-

I often have slides to display in class. I’ve used Keynote on my Mac for years. Keynote on the iPad pretty much displays whatever I create on my Mac. The latest version of Keynote supports the display of presenter notes on the iPad while displaying slides via the LCD. This is a key feature for me as it allows me to scroll through my lesson plans while a slide is being displayed.

Dropbox
——-

I used to copy Keynote files between my Mac and my iPad via iTunes. This is a huge pain. I now use [Dropbox](http://db.tt/PQBFBih) to have practically all of my files accessible from my iPad. I wish the iWord apps on the iPad would integrate seamlessly with Dropbox. No, I don’t want to use iWork.com.

1Password
———

Each of my logins is unique and relatively secure. I rely on 1Password on my Mac to manage this and it syncs with 1Password on my iPad. The 1Password iPad browser doesn’t work as well as Safari for some sights, but it works well enough for me to take attendance without having to type my log in information in every period.

Other Apps
———-

PCalc: I teach physics, PCalc is the best calculator.

iBooks: I don’t read many books on my iPad, but I reference a ton of PDFs.

YouTube and Videos: These apps support VGA output so I can share videos with my classes.

Limitations
===========

I still use my school-issued tablet when I want to demonstrate how to solve physics problems. I was given an Acase iPad stylus for Christmas. It works better for writing equations than the Pogo Sketch, but I wish it had a finer point. The best note taking application that I’ve found so far that supports VGA output is PenUltimate. However, I plan to try Note Taker HD soon. If you have any recommendations for another stylus or app that would be well suited for writing equations as well as drawing diagrams, please let me know!

There are many excellent physics simulations available ([PhET](http://phet.colorado.edu/) and [OpenSource Physics](http://www.compadre.org/osp/)). However, they require either Flash or Java. I’m tempted to compile my own Java interpreter so I can at least run some of the simulations but I really have better things to do. Hopefully, someone figures out a solution that is compatible with Apple’s application requirements regarding interpreters.

I occasionally wish I could display something via an LCD projector in an app that doesn’t suport VGA output. It would be great if the iPad supported universal VGA output (without jailbreaking it). It would be even better if it supported wireless LCD projectors (like the Epson one in my room).

Conclusion
==========

Overall, I’m quite pleased with my iPad at school. I find that the benefits outweigh the limitations and I can go find my school-issued tablet when needed. Rather than replacing my first generation Intel-based MacBook Pro this winter, I bought a 27″ iMac instead. The price of my iPad plus an iMac is less than a new MacBook Pro. In case you are wondering, I really like the 27″ screen.

Twas the Night before Kickoff

1 Reply

Twas the night before kickoff, when all through the school
Not a creature was stirring not even a ghoul;
The manuals were downloaded on the computer with care,
In hopes that decryption keys soon would be there;
The students were nestled all snug in their beds,
While visions of drive systems danced in their heads;
And I in my safety glasses with a three-quarter inch wrench,
Had just settled down with some parts on my bench –
When out in the parking lot there arose such a clatter,
I sprang from my stool to see what was the matter.
Away to the desk, I flew to my Mac,
Opened my browser, is security slack?
The moon on the breast of the new fallen snow,
Was pixelated by the camera we have there below
When, what see my tiring eyes with their gaze,
But an extra large crate, and eight tiny Segways
With a little old driver, so lively and keen,
I knew in a moment it must our Dean.
More rapid than the ship date his sponsors they came
And he whistled, and shouted, and called them by name;
“Now! Boeing, now! DEKA, now! FedEx and Delphi,
“On! NASA, on! Baxter, on! GM and NI;
As game pieces before the matches reside,
When they meet with a robot, no longer can hide;
So up to the loading dock the Segways they flew,
With the crate full of parts – and Dean Kamen too.
And then in a twinkling, I heard on the dock
The door rolling open, what of the lock?
As I quit my browser, and was turning around,
In the workshop Dean Kamen came in with a bound.
He was dressed all in denim, to his ankles at least,
And his clothes were all tarnished with solder and grease.
A bundle of parts was flung on his back,
And he looked like a MechE getting ready to hack:
The gears – how they twinkled! The motors: how many?
The wire was like candy, the encoders, a penny;
The number thirty-five chain was drawn up like a bow,
And the tread of the wheels was as white as the snow;
The soldering iron he held tight in his teeth,
And the fumes they encircled his head like a wreath.
He built a square frame, and a Mecanum drive
That rolled back and forth like something alive:
It was lightweight and sleek, with pneumatics to boot,
And I smiled when I saw it attempting to shoot;
A click of a relay and a turn of its tread
Soon gave me to know I had nothing to dread.
He spoke not a word, but went straight to the code,
Wired all the VIs; the cRIO did load,
And bringing his smartphone alongside his ear
And giving a nod, out the doorway he veered.
He sprang to his Segway, to his team gave a shout,
And away they all sped, I thought they’d wipe out.
But I heard him exclaim, as he drove without fear –
Gracious Professionalism to all, and to all a great year!

*Naperville, Illinois*
*7 January 2011*

Why Standards-Based Grading?

4 Replies

On Tuesday, the spring semester will begin and most of my students will be new to me and I new to them since classes get all scrambled between semesters. While everyone on my team structures their class according to our shared Standards-Based Grading (SBG) philosophy, I decided it would be important to share why I use SBG in my classes. I came up with five points:

* I want you to focus on learning.

Points and grades often get in the way of this.

* I want you to develop critical thinking and problem solving skills.

This requires you to take risks, make mistakes, and try again. You should be rewarded for this and not penalized.

* I want to know what you understand. I want you to know what you understand.

This requires frequent, useful feedback. 8/10 is not useful feedback.

* I want you to be responsible for your own learning.

This requires you to have the information, tools, and freedom to do so.

* I want your final grade to reflect your understanding of the standards for this course.

This requires grades to be associated with standards and you to have multiple opportunities to demonstrate your understanding.

What is important are these goals, not SBG. I have embraced a SBG philosophy only because it helps me and you achieve the above goals.

Teaching Energy

2 Replies

For the last couple of years, I’ve approach teaching energy from a conservation of energy perspective, deemphasized work, and focused on energy storage modes and transfer mechanisms. I think this has been very helpful for students, at least compared to starting with work and the work-energy theorem like I used to do. They understand the analogy as I pour water from the gravitational potential energy beaker into the kinetic energy beaker as the cart rolls down ramp. Students seem to more readily appreciate the idea that energy is always conserved, and, if a system doesn’t have as much energy as it used to have, we simply need to find to where it was transferred. It’s like a mystery.

This year, I’m trying to leverage as much of the [modeling methodology](http://modeling.asu.edu/) as I possibly can which includes energy pie charts and bar charts. As usual, I started conceptually and avoid numbers. We drew energy pie charts for various scenarios. Here’s an example from the Modeling curriculum:

energybarchart.png

Students readily understood and easily created these visual models and seemed to appreciate that they could actually handle real-world aspects like friction. If an object was sliding across the floor, we would include the floor in our system so that the total energy in our system, and, therefore the size of the pie chart, would remain constant as energy is transferred from kinetic energy storage mode to the internal energy storage mode. No problems here.

We then moved to energy bar charts but continued to postpone introducing numbers in Joules calculated from equations. Students had little trouble with this visual representation. For the object sliding across the floor scenario, most groups continued to include the “surface” as part of their system such that the total energy in the system remained constant and no energy flowed out of their system. For a scenario where someone pushes a box up a ramp, some groups wanted to include the person in their system, but after a discussion of the complex energy transfers that occur within the human body, they decided to keep people out of the system and include energy flowing into the system.

We started having problems when we started calculating specific energies. Students continued to want to account for energy being transferred to the internal energy storage mode. So, for example, when asked to calculate “the average force exerted by a ball on a glove,” they would get stuck trying to calculate how much of the kinetic energy of the ball is transferred to the internal energy of the ball and how much is transferred out of the system by working. I felt like an idiot when my response was, “well, since we don’t have a model that can help us calculate how much energy is transferred to the internal energy of the ball and how much energy is transferred outside of the system, we’ll have to assume that all of the energy is transferred outside of the system.” The students looked at me with that expression of, “you have gotta to be kidding me; if that is the case, why have we been including internal energy all this time?”

Basically, we stopped including internal energy in our quantitative energy bar charts and always had energy be transferred out of the system. With the aid of this visual model, students would consistently solve relatively complicated roller coaster problems without making the typical common mistakes. I could honestly tell my classes, “those of you who drew the energy bar charts, solved this problem correctly, and those of you who didn’t bother, didn’t.” Despite this clear improvement over previous years, not having a clear rationale for why why we handled internal energy differently in the quantitative bar charts compared to the conceptual visual models was disappointing. I’m sure the students were confused by this.

Suggestions for next year?