Introduction

I am a high-school teacher who really loves teaching and really loves computers. The digital revolution has resulted in amazing tools that have helped me immensely in the classroom. The internet revolution has put me and my students in touch with seemingly unlimited resources that have informed and enriched the classroom. The social media revolution is just underway, and it may prove to be even more disruptive to long-standing practices and attitudes in the classroom.

I am proud to have recently completed a graduate program from which I learned how to work with this new revolution as fruitfully as I have with the preceding ones. And who knows what effect this revolution, and my graduate program, will have not just on my classroom, but on my own profession. Disruption does not have to be a bad word.


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Monday, August 13, 2018

Space Junk Joyride

I don't get nearly enough chances to use Celestia in my classroom. I've loved messing around with Celestia for years, but it's the rare student who shares my enthusiasm for astronomy. In class I will use Celestia to demonstrate gravitational orbits - moons around planets, planets and comets around suns, stars orbiting stars orbiting more stars.

During one such class this past year, one of my brightest students asked me if I had heard about the time an asteroid had circled Earth three or four times and then disappeared. I encouraged her to explain further, though I was skeptical. So she whipped out her smartphone, found an animation of the event, and showed it to me. Sure enough, there it was.


The animation had specific dates, and the asteroid had a designation that I recognized as legit; J002E3. I promised the class that I would gather more information for the next class.

Wikipedia has an entry about J002E3, and in that page I found the NASA/JPL animation my student had shown me. I also found an amazing story. J002E3 was indeed first thought to be an asteroid, but later determined to be space junk, namely the third stage of the Apollo 12 Saturn V rocket launched in 1969. The rocket stage was intended to wind up in orbit around the Sun, but it didn't quite make it, and is now technically still in orbit around Earth. It's in a semi-stable orbit, though - J002E3 spends decades circling the Sun before it re-enters the Earth-Moon system, circles the Earth a half-dozen times, and gets shot back out around the Sun. Eventually it will crash into either the Earth or the Moon.

J002E3 orbited the Earth six times from the spring of 2002 until late spring of 2003, and this is what the animation shows. I presented the animation to my students on the SmartBoard, and I knew right away that I would have to change it. The file is an animated GIF, which cannot be paused, have its speed changed, or be run in reverse. The deep blue orbital path, which shows up nicely on a computer screen, did not project brightly enough on the SmartBoard to be seen easily. The GIF's dimensions were too small. I would have to do a little editing and then turn it into a video.

Photoshop is the perfect tool for this. It will read all the frames of an animated GIF and turn them into individual layers. You can edit the layers, and then turn them back into a GIF or a video. I first changed the dimensions, doubling both the width and height. Then I changed the color of the orbit in each of the frames. This took some painstaking effort - about 80% of the work could be done very quickly, but each of the 516 frames had to be carefully checked. I exported it as an MP4 video which I posted on YouTube.



NASA link: https://cneos.jpl.nasa.gov/news/news134.html
Animation versions & credit: https://cneos.jpl.nasa.gov/doc/j002e3/

Cross-posted to Teaching Is . . .

Friday, July 13, 2018

High (Voltage) Wire Act




My brother-in-law Peter visited last year and showed me and my wife some of his favorite short videos on YouTube. When I saw this one featuring a man inspecting high voltage lines, I knew that I would show it to my students. It's a lovely little video narrated by the electrical inspector who talks about his work, and his life, and even tells a story about how his suit is a special kind of Faraday cage.

I knew my students would find this video interesting. There are a lot of intriguing electrical details and small events that could almost go unnoticed, and which could form the basis of some interesting physics questions and demonstrations. Our technical school has an Electrical Technology shop, and students in the shop would already know about this kind of work, and would be excited to watch this and share their knowledge. This video is a perfect example of what I like to add to my instruction toolkit.

The version I first watched on YouTube was of poor quality, and there was no indication of who actually made the video. It was obviously clipped from a longer video about dangerous or exciting work. There are many copies scattered throughout YouTube, and I spent a lot of time hunting for the best and most complete version. I finally found a high-definition version of the clip. I used Filmora to clean up the beginning and the end of the audio track. I did watch other videos about high-voltage line inspectors, but this one best suited my purposes. It's calming, actually, rather than all hyped up, and you get a sense of the man rather than just a focus on the details or the danger of the job. The music sets the mood perfectly. There's a joke at the end that mostly goes over my students' heads.

I eventually discovered that the the clip is from an IMAX movie called "Straight Up: Helicopters In Action." It was produced in 2002 by SK Films for the Smithsonian National Air and Space Museum, and apparently aired as a cable TV broadcast by INHD, which later came to be called MOJO HD. I also came across a comment that it had appeared on Discovery HD.

Cross-posted to Teaching Is . . .

Thursday, July 5, 2018

The Electromagnetic Spectrum

A couple of years ago, when my team of physics teachers started building instruction around the topic of electromagnetic radiation, I began assembling a list of different common uses of EM radiation. This list would provide a basis of information to use in our written instruction, as well as suggest hands-on activities, demonstrations, and labs.

I focused on uses that high-school students would be familiar with; cellphones, wi-fi and bluetooth, radar guns used to clock car speeds, microwave ovens, various remote control devices, tanning lights. My school is a technical school, so students have familiarity with other uses and devices; arc-welding, dental x-rays, high-voltage power lines, baby monitors, visible light and color. By focusing on what students might be familiar with, I hoped to reveal both prior knowledge and prior misunderstandings and misconceptions. A teacher could build on the prior knowledge, but more importantly would be obliged to address the misconceptions.

The list became a full table of data, with over 30 entries. It has become an object of study in itself, an exercise in the literacy of reading data tables and extracting useful information to answer questions and solve problems. This is a form of literacy familiar to our technical students, who in their shops must learn to read technical manuals full of similar tables.

The full table is shown below:



As usual for me, the table was constructed as an Excel file, making it easy to add or change data. If you have access to Adobe Acrobat Pro, you could also edit the PDF version. Here are the links for both versions:

Excel file, with instructions
PDF file

A very helpful online calculator and table: https://rechneronline.de/spectrum/
Another online converter and source of information: https://www.translatorscafe.com/unit-converter/en/frequency-wavelength/

Cross-posted to Teaching Is . . .

Thursday, June 28, 2018

The Sun in Various Wavelengths

My physics curriculum has shifted in response to our new state frameworks, and one shift has been a greater emphasis on electromagnetic radiation. I've been having fun concocting new examples and demonstrations (including an "in-house" field trip to our metal fabrication shop to experience welding).

This spring my class was having a discussion about the Sun's radiation, and how so much of what it radiates is invisible to us. They wondered what it would look like if we could see the different kinds of radiation. I explained that we can create devices or sensors that detect different wavelengths of radiation, and then construct false-color images from the information gathered. Immediately I went online and hunted for something to show them. A great resource, which I have used before, is the wonderful and painstakingly-built website called Windows to the Universe. This site is a project of the National Earth Science Teachers Association.

In particular, I went to the page entitled The Multispectral Sun, and found this animated GIF:


I liked this concept a lot, and looked around for other examples. I found What's the Sun doing lately? and Compare Multispectral Sun Images, and lots of imagery, including this NASA composite image from the Solar Dynamics Observatory:


I decided to try making something of my own. My project would be a video replication of the animated GIF above, but using many more images. And I would start with the images in the NASA image above.

Here is what I wanted: a video file so playback can be controlled, a broad and representative spectrum of images, and captions with either a specific or representative wavelength indicated. I shamelessly borrowed some aspects of the animated GIF (images scaled to the same size, captions colored to match the image, images taken on the same day). Because I started with the NASA SDO chart, I needed to know what date those images were taken. A little hunting revealed July 11, 2012.

So I was off and running. I decided to stick with spectroheliograms, rather than dopplergrams or magnetograms. I searched for quite a while for solar images in various wavelengths that were taken on 7/11/12. Depending on what time and from where the image was taken, 7/10/12 images sometimes worked as well or better.

As I accumulated my images, I had to decide on wavelength units. My students didn't know about Angstroms, so I used nanometers instead. I came to realize that I could use just three units; nanometers, millimeters, and meters. Then came the laborious Photoshop work, including colorizing a couple of the images. The video was constructed and edited with Filmora. I posted the final video on YouTube.

An interesting issue is the color of the Sun as we see it. Ask anyone, what color is the Sun? Almost everyone will say "yellow," but of course it isn't, it's white, at least to our eyes. (Please don't go out now and look at the Sun - it's bad for your eyes. But if you have a chance to look at it when it's obscured by fog or clouds, you'll see.) I found many images of yellow suns with the caption "visible light." These images were either taken through a yellow filter or they were colorized yellow because of a belief people will think it should be yellow (white light, of course, does not have a specific wavelength).

When I showed the final video to my students, they loved it. But many suggested it should have music. I was telling this to one of my fellow science teachers, and she said, "I have exactly what you need!" She owns a small, portable planetarium called Star Theater Pro, and it comes with a music CD having 15 minutes of suitably cosmic-sounding music composed by Donovan Reimer. She was right, it was perfect.

Here's the final video product:



And here's a shorter animated GIF:


Here are links for downloading the most recent versions:
MP4 Video: 4 seconds per image, with audio
MP4 Video: 4 seconds per image, no audio
MP4 Video: 3 seconds per image, no audio
Animated GIF: 2 seconds per image, continuous loop

Credits:

Radio: 0.9 m, 2.0 m - BASS2000/Nançay Radioheliograph
Microwave: 17.6 mm - Siberian Solar Radio Telescope
Microwave: 52.6 mm - Nobeyama Radioheliograph
Infrared: 1083 nm - HAO/Mauna Loa Observatory CHIP
Visible: 656 nm (Hα) - Big Bear Solar Observatory
Visible: white - NASA/SDO AIA
Visible: 393 nm (CaIIK) - Langkawi National Observatory
Ultraviolet: 170 nm through X-Ray: 9.4 nm - NASA/SDO AIA
X-Ray: 5 nm, 1.9 nm - NOAA/GOES Solar X-Ray Imager

Music - Star Theater Pro/Donovan Reimer

Cross-posted to Teaching Is . . .

Wednesday, June 27, 2018

A Story About Weather and Teaching

Physics as Story

I think of physics as a kind of story. It's actually a huge collection of stories, the result of working to understand every physical phenomenon under the sun (and beyond). In the physics classroom I am therefore a storyteller, and I endeavor to help my students become better physics storytellers.

Certainly in physics there's a specialized vocabulary that can be assembled into stories, but I also think of graphs, diagrams, and even equations as kinds of story. As with any good story, there is an art and a craft to both the understanding and telling of physics stories. Physics stories just happen to be demanding in particular ways.

High school students already know how to tell many kinds of stories. I teach juniors and seniors, and they tend to tell certain kinds of stories about the events in their lives. For instance, many of them have begun driving cars, or are about to, and there is a lot of interest in and concern about driving. Some have already had scary experiences and close-calls; few have an accurate understanding of the physics of what they are doing. A natural entry point, then, is to ask them about their driving experiences. Various instructional activities give them the opportunity to refine and change their stories. If a student can tell a solid physics story, by whatever means, to whatever extent, then that student is demonstrating learned knowledge of physics.

A Worksheet as Storytelling

An instructional tool I have used for a long time is the vocabulary worksheet. You know the kind - there's a word bank, and you fill in the blanks to complete the sentences. But my worksheets have a different twist. Most of the words in the word bank are used several times. Each blank is numbered, and if a word fits the blank, it fits all the blanks with that number. This allows me to avoid writing disconnected sentences with only one or two blanks. I can write a coherent paragraph, a whole short story. Sometimes toward the end of the worksheet the sentences are mostly just blanks waiting to be filled in. The repetition of words and phrases becomes an important part of adjusting to the new vocabulary.

After everyone finishes, we read the worksheet out loud, one student per sentence. Sometimes we'll go around the room twice. If there are diagrams or equations at the bottom of the sheet, interpreting them is part of the reading. The students really enjoy the challenge, even by the end of the year after we've done two dozen or so of these. Here's one:



These worksheets can be difficult to construct. I have written an Excel spreadsheet that helps me construct them. It allows me to just write the sentences as naturally as possible, while it keeps track of the blanks and the numbering and the word bank. You can download one here. You'll need to Enable Editing, and then Enable Content. Then click on the button labeled "Help."

The Story of Weather

So what about the weather? I have a few favorite physics topics, and weather is one of them. The problem with broad topics like this in the physics classroom is that students are struggling to learn the basic concepts and tools, and weather is a really complex topic. Still, whenever there is a good opportunity, I'll try to link some aspect of weather to whatever we're working on.

The topic of heat and heat exchange is central, for instance, to weather. Before students can begin to comprehend this story, they need to master some basic ideas and vocabulary about heat. In my classes, this work tends to happen toward the end of the school year. If I have a class that seems ready, and there's a bit of time in the busy end-of-year schedule, I have a special worksheet for them.

Or rather I've been planning a special worksheet for which there keeps being not enough time to finish and use. Not enough time for the last two years. This year, because I knew I had the students who could benefit from it, I really hustled to finish this special worksheet.

I started with a simple but long vocabulary worksheet which tells the story of how the interaction between the atmosphere and the sun's radiation results in a rainstorm. The worksheet is simple because there are only six words in the word bank! But there are 20 sentences. After I finished the basic worksheet, I got the idea to use diagrams of the entire heat process that would parallel the sentences. I used diagrams from the National Weather Service's lovely tutorials on weather called JetStream. I edited the diagrams with Photoshop, and then used Adobe Acrobat Pro to assemble my worksheet.

I decided to split the page vertically and have the running vocabulary/story part on the left half and the images on the right half. I then put fill-in blanks on the diagrams which corresponded to the vocabulary. Normally my worksheets are black-and-white, but I decided to keep the images in color and to print the worksheets using a color printer. This emphasized the "special" aspect of this worksheet (and the students who got a worksheet all said "Ooooh, color!")



While the students were working on it, I looped a time-lapse video on the SmartBoard that showed a collection of rain-clouds billowing way up into the atmosphere. It was the last vocab worksheet of the year. As usual, we read it aloud once everyone finished.


Cross-posted to Teaching Is . . .