Friday, January 29, 2016

Dial it down a notch

As a mom I am surrounded by noisy things. Not just my kids but their accessories. It seems every toy nowadays has a speaker in it and they rarely have a volume adjustment. Most of them are at a reasonable volume although they will still startle you if you unwittingly step on them.

Then there are the LOUD ones with volumes that can only be described in all caps. You can hear them sound across the house and they are the ones you hope bleed the batteries dead quickly. (They never are.) This game, in an unassuming cute telephone, starts as you pick up the handset and using the plastic tabs that reside inside you can play several games to practice counting, number recognition and more. Seems innocent, and educational right?

Wrong. The thing is LOUD. Loud enough to drown out any conversation while it is speaking. And it will speak as long as it wants, until you replace the handset. Which can come detached by the way, great design flaw. There is an on/off button but no volume control. So one night I had had enough.

I removed the tab holder that twists on to the bottom and removed four small screws that held the blue base to the white top. I found the speaker and was surprised at the size of it compared to the toy. Since I had two very upset children demanding, "Momma, why broken? Momma fix!" it was going to be quick modification without rewiring. After the fact I found this nice instructable with details on adding a resistor to lower the speaker volume. But Momma didn't have time for that.

Ideally I would have found a scrap of cloth to fit over the holes that the speaker fit up against but the lower lips were starting to protrude from my kids' faces. So I cut a few post-it notes and layered them over the holes from the inside of the phone. I think I ended up with five pieces of paper covering it with some scotch tape. The blue housing you see around the speaker slides into the space right in front of the post-it notes in the photo below. In retrospect if I had used cloth it may have been a tight fit getting the speaker back in its place. Upon reassembly it was noticeably quieter.

Now the children can play the game and I don't have to hear it from the other room. And I can present this problem to my students, perhaps as an open ended engineering thought problem. Since we build speakers in our electromagnetism unit (post sound unit and electricity unit) after they create one I can ask students how to lower the volume with a few restrictions:

1. How could you lower the volume by only changing the circuit? (lower current, raise resistance)
2. How could you lower the volume by only changing the speaker? (decrease magnet or electromagnet strength)
3. How could you lower the volume by only changing the outgoing sound wave? (impede the sound waves' travel to your ear)

I've already started a mental list of which other toys need this treatment. Perhaps my in-classroom school intercom ...

Wednesday, January 27, 2016

Scientist Valentines: The Next Generation


I've been sharing my collection of Scientist Valentines for a few years now. I had a great time producing them. It's a nice mix is content knowledge, creativity, and graphic design.

Scientist Valentines

But why keep the fun to myself? I decided it might be fun to have students try their hands at producing Scientist Valentines. So I put together a set of instructions, and have now shared those instructions with my AP Physics 2 students. They were recipients of these valentines last year, so they likely understand the nature of them.

I have no idea what they'll come up with, but that's why I'm doing this. As I said in my Dank Memes post, physics is easy; comedy is hard.

I provided a list of science luminaries that I had not yet valentined. But they are welcome to go "off the grid" and valentine scientists I didn't list. They can also re-valentine a scientist I've already honored.

I've designated Scientist Valentines am extra credit project. It seems wrong to force students to produce such a thing if they are not motivated to do so. Here are the instructions.

Make Your Own Scientist Valentine (a.k.a., The Next Generation)

I'll share the best of what my students come up with. And I'd be delighted to see what your students come up with.

Sunday, January 24, 2016

Here Lies A Great Lesson

We've all know those teachers that have their lesson plans set in stone from year to year. I met one once while I was still student teaching that had a ledger filled with his lecture notes, discussion questions, etc. He would open the book at the beginning of the period, read through as much as they could get in a period, replace the bookmark and close it to repeat the next day. Rumor was he was still using the same curriculum he had "perfected" 30 years prior. He also napped during his prep period; obviously he had this teaching thing figured out.

Hopefully if you're here you aren't "that teacher" and you are probably continuously adjusting your curriculum. Big or small changes, for me at least lesson planning is eternal. Sometimes I have to decide which lesson will bring the most benefit to my students for their time. Which fits their current understanding? Which will help solidify that one concept they just haven't completely grasped? Those are the good choices, when you can look at a plethora of material and have the luxury of cherry picking the best of the best for your students.

More recently though my choices have been made for me by outside forces. Sometimes I don't have the equipment or materials but more often the resource lacking is time. It takes time to help students truly understand concepts. Strange concept, right? Sometimes we run short on days in a unit as we back up to a vacation or there is a rally or a minimum day or what has been all too frequent lately, a bomb threat. Or if students don't understand the concept a single day's lesson plan can become two, or even three. You might find yourself crossing off the things you don't get to do. When I make that lesson plan edit that pushes a great activity off for another year I can't help but be sad.

Wallowing in your grief, ("This would have been SO great!" [sniffle]) doesn't help your students. So how do you make the best of the bad situation? Here are some tips, not all will fit every situation, you'll have to make another choice. ;)

1. Trim the fat. You mean you want me to cut MORE? It seems counterintuitive but cutting out unnecessary activities can help you carve out enough time to fit in the lesson you really wanted to do. Maybe they only need five practice problems not ten? My filing cabinets are full of activities that used to be my favorites; until I made better favorites.

2. Push it all back. If you have fat you can trim in a later unit, mentally take some of those days and push your current unit back so you can do the lesson you wanted to do. This can have a runaway effect though, and you find you really run out of time at the end of the term.

3. Adjust the format. Can your activity be done in groups instead of individually? In class instead of at home or visa versa? If you can adjust the format of a unit you might be able to fit it in in place of another. There was a recent post about a 20 minute format of a lesson. Sometimes shorter is sweeter if it means your students actually get to do it.

4. Save it for next year. I make notes on my lesson plans about the activities I didn't have time for, especially if I've already got copies made. If you don't make yourself a reminder where you'll see it at the beginning of the unit, you may run into the same issue.

5. Built in review, anyone? Depending on the activity it may help students review those concepts later on be it end of unit or end of semester. Why not use it to review concepts or practice when students need it before a large assessment?

Sometimes it just doesn't work out. Being disappointed that you didn't get to do an activity is one of the weird parts about teaching. I pout a bit thinking that I have to wait a whole year before I get to actually do it. Its a good thing we get a fresh start every year, another trip around the sun!

Ninth Planet?!

I just finished my mini Astronomy Unit in my Conceptual Physics classes so my students are very space-centric right now. Many of them approached me very excited about the possibility of a(nother) ninth planet that has been in the news. I did tear up a bit with pride when they were able to discuss if it would be a real planet as defined by the International Astronomical Union. We discuss the changing critera for planethood when we read The Pluto Files by Neil deGrasse Tyson and how that mirrors how "real science" is done. If you're interested, my Pluto Files curriculum that follows the book is here.

The IAU's current definition of a planet (as discussed here with a history of Pluto) is:

A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

That  last part is what kicked Pluto out of the Planet Club; it's orbit is littered with other Kuiper Belt Objects including objects that are the same size or even larger, like Eris. Now such objects are considered Dwarf Planets because they meet the first two criteria above but not the third.

Although this potential ninth planet, called Planet Nine, has not been directly observed or photographed, evidence of its existence was strong enough to prompt Cal Tech researchers to make the announcement last week. Mike Brown and Konstantin Batygin found perturbations in the orbits of other Kuiper Belt Objects that they feel must have been caused by a planet ten times or more larger than Earth. This is how Uranus, Neptune and Pluto were found although the movement caused by Planet Nine's orbit is much more complex. This method of discovery is also something we discuss in class; when scientists noticed something off about the planets' orbits they looked for a reason. Investigation driven by curiosity! Below is an infographic from that summarizes the findings.

Saturday, January 23, 2016

Logic Gates: Boolean algebra meets simple circuits

Back in the late 1980s and early 1990s, I was slowly but surely amassing the empire of equipment I now leverage in my physics lab. Back then I felt a freedom to develop lessons and labs that were useful in teaching physics principles and applications. There were no content standards looming over my head. No Common Core State Standards to shoehorn my lessons into. No multicolored, multilayered, NGSS alignment demands.

Evidently, none of my students learned a thing about physics or science back then. Such a pity.

Once my lab was geared up for simple circuit labs with a full complement of batteries, bulbs, switches, and wires, I allowed my serendipity to wander. (I tended to do this whenever I got new apparatus.) I knew the standard things that could be done. But what else?

One such meander led me to develop "Logic Gates". Instead of connecting resistors or bulbs in series or parallel, how about connecting switches in series or parallel. The results were simple circuit representations of Boolean logic: realia that could be used to fill truth tables! (I studied Boolean logic and truth tables in high school math. Apparently that's no longer done.)

Since the very concept of Boolean logic was foreign to my students, I created a prelab exercise to bring them up to speed before launching them into the activity. It's the classic "Besse can get to her pasture if Gates A AND B are open…" story, with all requisite variations. Since a bright student named Haleh made a point to tell me how useful the prelab was, I named the worksheet "Haleh Cow!". It's what I do.

Once students have the hang of Boolean algebra (if-then, and, or), it's time to break out the circuit gadgetry. In the old days, we powered the circuits with batteries. Nowadays, we use Genecons (which are much more forgiving for the NOT gates).

NGSS doesn't call much for anything related to electric circuits. So this activity is relegated for use with AP Physics 2 students, only. In any case, here's the lab.

It should be noted (especially in light of Bree's insightful post) that this activity got pushed into dormancy when standardized testing was phased in. With AP1 and AP2, I have been able to dust off a few gems from bygone years. If I could reanimate my revisions of Dewey Dykstra's implementation of Fred Goldberg's optics learning research (from back before PER was a thing), that'd be great! 

Monday, January 18, 2016

An Object at Rest

The title of this animated short is a physics reference, but the content is ... well, see for yourself. You won't regret it.

Monday, January 04, 2016

Newly expanded and updated Power Balance lesson

When transforming all my curriculum documents from Canvas to Keynote, my Skepticism in the Classroom Power Balance lesson was missed.

So over the break, I fired up the 2008 MacBook Pro running Snow Leopard, and rectified the situation.

The original was done before I came across ESPN's Outside The Lines exposé. And Power Balance has collapsed is meteorically as they rose, so I added a section on the still-in-business-for-now Phiten Company.

The assignment works nicely for flipped classrooms. It can be an in-class assignment if laptops and headphones (and splitters) are deployed.

YouTube Skepticism: Power Balance & Mylar Technology (2016 edition)

The lesson draws upon multiple videoclips. My favorite is a follow-up to a puff piece, wherein skeptic Richard Saunders has a Power Balance promoter do the debunking work on his behalf.

Here's an earlier version featuring James Randi similarly using a believer to debunk the charade. Make a note to yourself that promoter-administered strength/balance tests (applied kinesiology) are the calling card of many modern-day snake-oil salespeople. Fellow physics teacher and skeptic, Matt Lowry, and I encountered such a salesman at the National Science Teachers' Association national meeting in Chicago last year. We tried to be civil to the poor guy, but he really picked the wrong two conferees to prey on. The guy didn't appreciate it when I turned the tables and ran his own tests on him. My buddy, Matt, was so bent over with laughter, I thought he was going to lose continence.

Anyway, back to Classic Randi.

Did you see it? The instructive moment? It's actually a standard moment in nearly every public debunking storyboard:

1. Challenger makes extraordinary claim.
2. Challenger and skeptic agree on a testing protocol. This is a very important step. Very important.
3. Challenger fails test. Utterly and completely.
4. Challenger insists the extraordinary claim is valid, but the testing protocol was somehow "rigged".

How could Randi have preemptively robbed the claimant of her post-failure excuse?

Sunday, December 13, 2015

Periscopes take 2 ... well 3

After I wrote the "Down Periscopes" post I bought more PVC, more plastic mirrors and planned to make a few variations of more periscopes. The 4" diameter PVC pipe I used the first time was a bit large and cumbersome for in-class demos if I wanted to use more than one at once so I decided to go with a smaller 1.5" diameter pipe. I had bought scrap plastic mirror from TAP Plastics and planned to cut them down to fit into the smaller PVC pipe since they didn't have pre-cut mirror pieces in a smaller size. My first cuts were too long to be at a 45-degree angle within the right angled ends. Life got in the way for a few weeks and when I went back to it after some home renovations, I hit a construction snag. We had managed to burn through, blow up or break the motor shaft of three different Dremel multi-tools during the remodel. Without a tool to make a clean cut on the plastic mirrors I opted for one inch square glass mirrors I already had in my class room. (I've already admitted to being a hoarder of potential equipment.) My son wanted to help, he thinks all my PVC parts are his building blocks.

I've made three different periscopes of the same length:
1. A periscope sealed on the end that goes into the water and is thus filled with air. (This could be sealed on both ends as with the original but it is not necessary.)
2. A periscope sealed on both ends and filled with water.
3. A periscope not sealed on either end which allows the water to fill it.

The periscope to be filled with water has a hole in it that fits a rubber stopper. I was surprised how much water the periscope took and you do have to rock the perisope back in forth to move the bubbles around. The periscope has to be filled with enough water to submerge both mirrors. I also quickly found that the hot glue leaked on the "sealed" ends. But the leak was slow enough that I was still able to conduct the experiments initially.

On the left, viewing a small tiger toy through the air filled periscope
and on the right viewing it through the water filled periscope
without both mirrors submerged. 
I put a few of my children's toys in the bottom of a bucket with a light directly above me and viewed the toys through each of the periscopes when holding the periscope vertically. I expected the air filled periscope to give a clear image of the toys as with the original, and it did. When I looked through the periscope that allowed water to get into it I could only see the surface of the water in the tube and a vague bit of color.

I expected the water filled periscope to be blurry, and it was, looking about the same as trying to view something under choppy water from above. The pictures were difficult to get with a camera phone as the images in the eyepiece mirrors were quite small. I found that the water level had dropped in the water-filled periscope so that only the bottom mirror was submerged. I had to try holding the periscope horizontally to keep both mirrors submerged in water. I found that the toy could not be directly underneath the mirror and be seen out of the other end.

At first I thought it was refraction, but the medium did not change as the light traveled from the water in the bucket to the water in the periscope. After thinking about it for awhile I realized that although I had planned to hold the periscope horizontally as per the picture below I did not hold it perfectly parallel to the floor. This would account for the apparent shift in position as the mirror was aimed at the toy but not directly above it. Now I'm happy my husband tried to take an "embarrassing" photo of me experimenting in my pajamas.

I did recreate the water filled experiment being sure to keep the periscope more horizontal and found the mirror to be nearly right above it. After some trial and error, a better camera and more caulking on the water filled periscope, I was able to get clearer images.

I found that even with caulking on the ends because the clear plastic circle sat on top of the 90-degree elbow instead of inside it as with my other model it was never going to be perfectly sealed. When I presented this at the Fall 2015 NCNAAPT Meeting & Conference at Sacramento State my water-filled periscope leaked quite a bit.

Through that presentation I was able to refine my plan for using these periscopes in class a bit more. Several members enjoyed playing with my periscopes but then asked, "These are great, but what are you going to do with them?"

I've decided that the best use of my periscopes is as a discrepant event. Students can either look through the periscopes individually or the image can be seen through a document camera. I can show students the view through the air-filled periscope which produces a clear image. Then I can show them the view through the periscope open to air and water which produces a blurry image. Based on these two experiences I can ask students what they would expect to see from a water filled periscope. After they have a chance to discuss it they can actually see the image through the water filled periscope which is about as clear as the air-filled periscope. I hope to lead this into a discussion about refraction.

The air-filled and water-filled periscopes produce about the same image because there is no refraction between the object, mirrors and then your eye. (Consider the small change through the plastic circles to be negligible.) Only in the periscope open to water and air do you see refraction at the water-air boundary that affects the clarity of the image you see.

Tuesday, November 24, 2015

Engineering A Dart Launcher

We have five Nerf-obsessed neighbor boys who regularly have team turf wars across our neighborhood. It is adorable and we always find the small foam darts tucked under bushes and shrubs. My two year old finds them all the time and triumphantly brings them to me (they have a "return" pile set aside). One of our neighbors was playing out front with a two foot white pipe and while I watched he launched a small dart easily 40 feet in the air! Needless to say I was interested, if this was a store made toy I knew what was going on my Christmas list.

I called him over and he was more than happy to show me. He had made it at a birthday party recently; I made a mental note to forgo goody bags the next time one of my kids' had a birthday. His PVC pipe is probably 3/4" diameter and had a balloon duct taped to one of the pipe. He had stuck a straw into a form dart and held it in place with more duct tape. My neighbor's model had camouflage duct tape down the side ("That's to look cool," he told me) and two straight end connectors on each end. He let me give his a go and I determined the end pieces were not necessary. Each time I played with it, ahem, experimented with the dart launcher I was surprised at the height it achieved.

It didn't take long for the dart launcher to catch my daughter's attention and she asked, "Mommy can we make one?" Well who can say no to that? I had already been taking a mental inventory of the PVC I had on hand so we headed to the garage. I sent my kids to find Nerf darts and I found two pieces of PVC that were too short for other projects. By the time they returned with Nerf darts I had procured straws and balloons. I cut the straight necks off the balloons and duct taped them to the ends of the PVC. The foam darts were put on to the straws and taped together. All in all it took me five minutes to build two launchers.

I did vary the launcher for my two year old for safety as seen above and left. His PVC pipe was much shorter and there was not as much give on his balloon. I pulled the balloon farther up onto the pipe so that it could not be pulled back as far. I also used a larger and heavier dart on his straw so that it wouldn't be able to go as far. Of course, he had trouble actually launching it anyway so I shouldn't have been too worried. 

My kids and our neighbor that had inspired it all happily ran outside to play with them. Our neighbor found that he could launch his original lighter dart in my son's "toddler safe" launcher just as high as his original. He liked the more compact version for mobile combat and spent the next hour running around the yard with my daughter chasing their darts. You can also launch a foam dart without a straw but it does not go as high as one attached to a straw. I was so impressed with the height of the darts I started thinking about how to use it in my classroom. I know, that probably comes as no surprise.

I found a simple plan on a "Frugal Fun 4 Boys" blog that was similar to what we had made. I decided that since the dart launcher has several launching variables I wanted to use it as an engineering activity. I wrote up an activity (remember its a draft format!) that explained how to make the small launcher and outlined an all-class competition. The plan is assign one launch variable to each group: launch angle, balloon pull length, dart weight, straw length, etc. Each group will test the variable for maximum dart range using identical launchers and then report their findings to the rest of the class. Ideally they are also practicing some data collection skills by being careful not to change anything but their assigned variable. The whole class should be able to summarize these findings and determine the best set-up for their dart launcher to achieve maximum dart range. I'm hoping to then test each class' optimum set-up against each other in an all-class competition. I won't be teaching projectiles until the beginning of second semester but I will let you know how it goes!

I plan on purchasing a few of these refill packs so I don't have to diminish our neighborhood ammunition supply.

Sunday, November 15, 2015

Dank memes

It's impossible to participate in social media without being inundated with images emblazoned with captions that overlie the images. These are not factually captioned photographs. These are humorously graffitied screen-captures or illustrations commonly referred to now as Internet memes ("meems"). The term, meme, refers to something else.

They are a sort of lexicon in Twitter, Facebook, and the like. A cultural fad, or here to stay? Who knows. In the meantime, I dipped a toe in.

I was first compelled to create a few in support of my "Equation, Rearrange, Substitute, Answer" recipe for students to use when solving problems. But the craft is limited only by one's creativity and comedic skills.

After posting a few in class, students wanted to join in. But they don't always have the same sense of decorum and propriety that sets boundaries on what a classroom teacher might feel comfortable posting.

One student aficionado referred to top-quality caption/images as dank memes ("may-mays"). I thought he was making it up until I found an online urban dictionary pronunciation. Dank meme can also be a sarcastic term for old / overly done memes.

When creating memes, the reflexive urge s to create "nag memes".

Encouragement meme are harder to produce. The encouragement element cuts against the sarcasm/humor element. One does one's best.

But wait. Why not make some with a physics theme?

I think it's important to "save a blade for yourself". It's no good to criticize the world with nag memes while holding yourself above the crowd. Easy? Yes. Comforting? I suppose. Good? No.

It's important to remember in all cases where social media and teachers intersect. I'll illustrate with news item headlines:

Teacher awarded prize for poignant Facebook post

Teacher fired following controversial tweet

One of these headlines is plausible. The other will never appear above a real news item. For teachers, there are two outcomes possible when participating in social media: nothing or negative. There are no positive outcomes. Only negative. Or—at best—none.

I generally trust colleagues to their best judgment to avoid creating memes that border on racism, sexism, etc. But at the last YouTube Physics session I hosted, a colleague traveled to The University of Minnesota AAPT SM14 and come to the session just to share this gem, which he thought was a great thing to show students in a physics class. So… yeah. If AAPT ever does a YouTube Physics session, it would probably be best not to use the "open mic" format.

So remember,

And be careful. You'll do better connecting the message to students if you know what the common use of a particular meme is. Once you know what the standard use is, you can bend it to your own use.

Here is a Dropbox link to the memes I've created: Memes

And I would be remiss if I didn't provide a link to Buzzfeed's 61 Best Teacher Memes.