2015.06.17 – Colonoscopy, joy!

[medical]

I had a colonoscopy (and upper endoscopy) for Wednesday, so starting Monday I started the ‘clear’ diet.. white rice, gatorade, and veggie broth. By Tuesday is was down to just gatorade and veggie broth.. which really didn’t bother me too much.

Tuesday evening I started the SuPrep… a sickly, sickly sweet solution that draws water to your colon like mad. I sipped the 16oz solution over about 30 minutes.. then had some watered down gatorade to get rid of the taste.  Then 32oz of water.

Honestly, drinking that stuff was the worst part of the whole procedure.

About an hour later, though my belly had been gurgling for 20 minutes, I was on the toilet. It wasn’t so bad.. just very watery. I read a book…. some Vernor Vinge thing… Fire Upon the Deep, not very good, but it passed the time until my guts settled down.
Once convinced all was calm, I went to bed.

The next morning, around 8, I drank the second round;   it was awful, disgustingly sweet, and so bad I can still taste it.
Twenty minutes later I was on the toilet again.

To be graphic, and possibly helpful… I was basically pissing out of my ass… for a while it was mostly an orange colored sediment kind of thing… the bowl would be not too far from opaque, and I was worried that my tubes weren’t clear enough for the inspection.  But after a while, the effluent became clearer.  It never got completely clear, but nearly so. And after seeing the pictures, mostly clear is good enough.
Begin the procedure:

(Yep, the sound is AWFUL..  but you can tell that being there would have been magical.)

Laying on a cart, with a needle in the back of my hand..

The anesthesiologist pushed on a syringe feeding a vein in my hand and said, “you’ll fall right asleep now”. I started to say something, felt a swarm of weirdness crawling up my arm.. it crept upwards, to my shoulder, 4 seconds later, reality was being devoured by the bliss of drift…   “sleep”.

I woke up, unaware of how long I had “slept”. A welcomed, long-awaited sleep as I have not had in months… years, perhaps.
I dare not ask what the drug was.

After awakening, they gave me crappy snacks (why?!) and then my wife took me to the car.
Groggy, but pleasantly so.. and, I think, mostly coherent.

No pain at all.  No discomfort.  Just back to normal, minus being drugged out.
Hung out with the neighbors, started to watch Game of Thrones…   all ok…    then bam!!   MaSSIVE headache unlike anything I’ve ever had before.

Laying down made things worse.
Took some ibuprofen.
Puked them up.
Took some ibuprofen.
Puked them up too.
Tried to guess at how much I might have absorbed.
Took some ibuprofen.
__Stood__ still, for a while.  Lying down made the pain worse.
And everything balanced after a while..

Nothing else to report.

Oh..  results…    um, 3 polyps… all ok.
I have some esophageal damage from reflux, despite never having felt anything.

All together, not my idea of fun but not as bad as I had feared.

20121121 Malcolm X

20121121 at Malcolm X Elementary with Ms. Crawford’s 3rd grade girls and Ms. Livingston’s 3rd grade boys.  I tried the statistics with M&M’s and a little bit of introduction to ratios, measuring, etc.  Basically neither class went well.  The concept of ratios needed more explaining than could be quickly done, transforming their measurements from ratios to decimels was too advanced, and trying to back-pedal to just comparing numerators to denominators to see which was larger was a challenge.  For the most part, the M&M’s worked well.  I explained how extra candies would be left with their teachers, but that for our classwork the candies would be used and thes discarded.  Everyone tallied up their colors and some even pro-actively summed totals from other students.  But I seemed to miss getting across the idea that there was a randomness, something that could be characterized but never nailed down. 
They very much enjoyed measuring lengths and were aware of the metric system and the empirical system.  They learned how to measure something that was longer than their tapes. 
On the whole however, I came in stressed from work and wasn’t able to get my thoughts together.  The students can sense something is off very quickly, and the class simply runs rough.  The teachers were clearly aware that the lessons weren’t’t going very well and tried to help where they could.  In the end I just gotta chalk this week up as a miss and move on.

Malcolm X

14 Nov 2012 First time teaching at Malcolm X Elementary school. Ms. Crawford’s 3rd grade girls and Ms. Lexington’s rd3rd grade boys. I came in blind to what their current lessons were covering, and chose to go with something very interactive, with broad ideas, namely electricity. Standard warnings were given, that some of the topics topics would be years ahead of where theywould normally be exposed to and that they shouldn’t worry about it too much. They were also told to expect a certain pattern in the lessons. Each would start with a bit of lecturing which might be a bit trying to maintain focus through, but that they shouldn’t fret, the majority of the class would be , usually, more hands-on. So we talked about matter and elements and atoms and atomic particles; neutron, protons, and electrons. I simply jumped into the idea that electricity is the movement of electrons.. Understand that they had never heard of elements, let alone atomic structure. So, we talked about insulated and conductors, and then on to electric circuits. I compared it to piping water.. There has to be a complete circuit, any break would disrupt the flow, etc etc. We then walked through, with their patience waning, a circuit consisting of a battery, a wire, and a light bulb. This was followed by the distribution of 2 batteries, ` wire, and 1 flashlight bulbs to teams of 3 students each. As before with this lesson, successfully lighting the bulb for the first time is a bit of a challenge. It was good to assign students to each of the components. They get quite a kick out of their first success. Having learned just how fast they move on to exploringwhat else they can do with the parts from previous classes, I gave them no further instruction on what to do next. A few asked of there was more to do, or if they were going to use the other parts… I simply announced that, having succeed in lighting the light bulbs, they may wish to consider what else could be done with what they had at hand. Within a minute or two excited cries started up exclaiming how someone had managed to light bulb1 bulbs at once, or make them brighter by using 2 batteries. It’s one of my favorite parts of all the lessons… they really get engaged and excited about exploring. I think it also lets them feel in control of something, it’s a small step outside of the usual experience of being led or called all day long. Or so I imagine. We had time in our science hour to do both this lesson and one about static electricity. The CDI (2 small strips of aluminum foil suspended from a paperclip) didn’t work very well, I suspect the air wasn’t quite dry enough. We did play with charging Styrofoam blocks by rubbing wool on them. After charging one, throw an aluminum pie pan on top (“throw” is a critical word here), then the students can get shocked by bringing a finger close to the edge of the pan. They’ll also find they can lift the blocks with by the pan sometimes. I still have the problem of making a Styrofoam mess. Given that this was my first time with these groups I believe it went very well. As always some parts worked better than others, but on the whole the students were lively, engaged, and picked up on more of the ideas than I would have guessed. As a private note, it seemed that the girl’s class was more focused and quicker to grasp ideas.

Electricity

sorry, never formatted this one..

4 Jan 2012, 3rd Grade, Patterson Elementary School, DC. Atoms, and batteries, and lightning…  oh my. This week, electricity. “Does anyone know what we call the smallest piece of matter?” – silence – So we began with a simple description of atoms and their subparticles.  The point being to talk about electrons and how they behave. Electrons have a negative charge.  Like charges repel.  Opposite charges attract.  Electrons can break away from atoms and move relatively easily in materials like most metals, these are called conductors.  They have a really hard time trying to move in materials like glass, plastic, or other insulators.   I described a circuit as a power source having a positive and negative tap that are connected by a closed loop of some conductive material.  On the board I sketched out a battery, wire, and a light bulb all connected in a loop.  We went over the movement of electrons from the negative tap through the wire, through the filament where it encountered resistance and produced heat and light, and then to the positive battery terminal. After the first class I learned that it was worth taking the time to reiterate that if any of the connections were broken, the electric flow would stop.  It was also a good idea to describe the connection points on the bulb and the fact that they are separated by in insulator…   which means what, class?  Finally they were shown where the battery terminals were. Working in pairs the supplies were distributed; 1 piece of insulated wire with the ends stripped, 3 batteries (C or D size), and a bulb from a 3 volt flashlight.  One student would hold a battery with one end of the wire touching the bottom terminal.  The other would place the base of the bulb on the top of the battery and then touch the free end of the wire to the side connection of the bulb.  Without the distinction of the bulb’s connection points many students tried placing the wire to the base of the bulb, shorting out the battery. This step takes a little bit of time and some individual attention.  By the time everyone had succeeded in reliably lighting the bulb at least one group had already started to stack the batteries and increase the bulb’s brightness.  This happened in both classes. I love little things like this.  There was no previous mention of using multiple batteries.  (Of course they did have the materials in front of them.)  One class even ventured into lighting up more than one bulb at a time.  And, yes, one group went a bit too far and fried a bulb.  I brought extras. They would continue tinkering with these kits for as long as you would let them.  I collected the materials and we talked about what observations they had made.  This was a good time to do a little math having volunteers add up voltages on the board (1.5v per battery).  With 4th graders I would probably go into the analogy of voltage as water pressure and current as water flow. Switching gears to static electricity we talked about lightning and scuffling shoes on a carpet in winter.  I had made a highly sophisticated charge detection instrument (CDI) which I had a student hold.  This finely crafted device was made of 2 small strips of aluminum foil about 1cm wide and 5cm long.  Holes were punched near one end of both and they were loosely strung onto a paper clip.  Somehow the students were not impressed. I held up a block of styrofoam from some packaging material and described it as an insulator.  I held a piece of someone’s old wool sweater in my other hand.  Admitting ignorance of the details, I mentioned that as I rub the styrofoam with the wool electrons would be deposited on its surface.  It being an insulator the electrons were then pretty well stuck in place. Standing several feet away from the CDI, I rapidly but lightly rubbed the styrofoam for 5 or 6 seconds.   Then making sure the assistant held the CDI up high where all could see I slowly brought the foam toward it.  At around 3 feet away the foil began to move and at 1 foot the strips were splayed wide.  If the foam was moved away the foil, mostly, returned to simply hanging down. Now the students appreciated the amazing CDI! Luckily the classrooms have a faucet and sink in them.  I turned on a small steady stream of water and charged up the foam again.  As the foam was brought towards the flowing water the stream began to deflect towards it.  The effect last for a few seconds and can be quite dramatic.  I should have had a volunteer do this. If there is time.. On the board I drew a diagram of the styrofoam, charged with lots of electrons stuck on it while it rested on a table.  Then I drew the pie pan on top.  If electrons were free to move in the metal pan, but the charge on the foam was stuck, what would happen? We would find out by charging the foam, laying it down, and then dropping the pan on top if it.  Then the students could approach the side of the pan with their finger.  It was important to be clear that getting the pan onto the foam without touching it was crucial. Blocks of strofoam, wool, and aluminum pie pans were distributed to the students and they began to work.  Quickly shouts of surprise started up as the students were shocked.  Most would try touching the pan over and over hoping for an additional shock.  This was an opportunity to reiterate the lesson and get them to walk through what was going on. There are many things the students can try with these simple tools and they’ll explore on their own if allowed. Balloons are also fun and easy to charge.

Pi, Other Ratios… and goodbye?

11 Jan 2012,  Patterson Elementary School, DC.

I’ve taken a new position as an electro-optics infra-red engineer.  So, for now, I won’t be available to teach during the day.  Hopefully I can convince the management to let me flex out the time to teach.  We’ll see.

This week, though, we started by examining circles.  The students were each given a cloth tape measure and asked to find something around the room that was circular which could be measured ‘around’ and ‘across’.  Luckily there were plenty of large plastic lids of different sizes available, these ran from 5 to 12 inches in diameter.  Next time I would bring a collection of objects to measure, the students got a bit distracted while locating their circles.

A diagram on the board and a demonstration of the two measurements helped clarify the process.  I needed to emphasize repeatedly that they should write down their findings.  Some students continued to measure different circles while waiting for everyone to complete the task.

Next they were asked to divide the circumference by the diameter.  Given the limited time and the accuracy of the measurements I asked them to just get leave any partial amounts as a fraction.  After walking around and helping a bit I recorded their findings on the board.  The values ranged roughly from 2 1/2  to  4, with a lot of 3’s.

No matter what size circle they had measured the ratio always seemed to be about 3.    🙂
I introduced the Greek letter ‘Π’ and the idea that all circles have this same ratio.  While explaining that Pi has an infinite number of decimal places I told them that 3.14 was what we would use for now.  I didn’t succeed in impressing how cool this was.  I tried to explain that any circle anywhere would have this same ratio, but…    Some kind of build-up before beginning to make the measurements might have helped.

Next we switched to physical anthropology and made various body measurements.  Height, arm span, ankle to knee, knee to hip, hip to collar bone, shoulder to elbow, elbow to wrist, head circumference, and the lengths of the 2nd and 4th fingers (index and ring fingers).   This was great fun and good practice at measuring, recording data, and working cooperatively.

If there is time you can measure your own (or any adult’s) height and arm span.  Earlier in life our span is significantly less than our height but as we physically mature that ratio changes.
Another interesting ratio is the 4th to the 2nd finger length (use the dominant hand).  Although at first I just thought it was an old wives tale, I found respectable  articles describing that the more testosterone there is in a body, the longer the 4th finger will be relative to the 2nd.   I had hoped to have the students calculate the ratios and then line up in order and ask if they see a pattern.  They would be ordered by gender.  We didn’t have time for this, but I did run around and check everyone’s hands.  There was only one exception among the nearly 40 students.       ….which may have caused that student to feel a bit uneasy.   (Maybe I could have ‘examined’ the outlying students and ‘corrected’ their results…  I dunno.)

Gelatin Optics

In teaching third graders some basics about optics I thought that gelatin lenses might be a fun way to introduce various aspects to the students.  So, I bought a bunch of Knox Gelatine.  This is basically non-flavored, non-colored, non-sweetened Jello.

It’s very easy to make.  Just add a packet of Knox to 1 cup of hot, near boiling, water.   Some people have suggested doubling the amount of gelatin per water.  I tried this, but found it unnecessary.

Forming various shapes can be done by either cutting up sheets of set gelatin, or using different containers to form shapes directly.

If you decide to cut out shapes you’ll probably have surfaces that are not very smooth.  Perhaps these could be “sanded” down with a bit of warm water on a sponge or something, but I just left them rough.  They worked… mostly.

I tried using a large glass to form a plano-convex lens.  Which worked just fine.  However, the curvature is a lot more than what I’d really like to use.

 

Final verdict:
This didn’t work out so well.  

Optics big time fun

9 Nov 2011,  Patterson Elementary School, DC.

I’ve played around with using gelatin as a form of simple, easy to form lenses.  It works ok with the $1 laser pointers, showing the beam path quite clearly.  Internal reflections are possible.  Lenses behave as expected.  It would take too long to make nice clean surfaces, but the rough cuts made with knives or cookie cutters are useful in spots.  See Gelatin Optics

—

The Optics Society of America provided small simple kits for covering, in this case, three topics.  Polarization, diffraction, and third one I’ll describe later.

I began by drawing a prism on the board and describing how ‘white’ light is the combination of many different wavelengths.  When light enters a prism it’s path is bent, with short wavelengths being bent more than long ones.  (I skipped talking about wavelengths specifically.)  So as it exits the blue light in bent more than the red and thus the white light is spread out by color, making a rainbow.  This bending of the light is known as refraction.

In retrospect it may have been better to talk about refraction without bringing up wavelengths or color.  That would make it easier to talk about lenses in general and perhaps bring up the marching soldiers and mud example of explaining the index of refraction.

Next I drew an eye on the board.  This proved to be far more interesting to the students than I had guessed.
I had all the basic components; optic nerve, retina, lens, cornea, iris/pupil, and the muscles that move the eye.   I did not go into cones and rods.

One on two students went, “eeewwwwww” as we talked about the various parts.  Many had questions and ideas.  Some didn’t believe that the image on the retina is upside down.
I finished with the lens and the cornea (which also acts as a lens).

Questions came up and we talked a little about glasses and contacts.

The first kit we opened up contained a small filter with a diffraction pattern etched onto it.  I described the filter as having lots of tiny lines scratched onto it like a DVD.  Glossing over why, I simply said that the diffraction pattern was somewhat similar to a prism in that it would spread white light out into its various component colors.   They then took out their gratings and looked through them.  A small incandescent flashlight was included which the kids enjoyed.

After letting them play for a minute or two, we aimed the small laser pointers I had brought through the filters.  I explained that the light from the laser was made of only a small range of wavelengths that happen to be red, that this was not ‘white’ light and that it didn’t contain the other colors like blue, yellow, or green.  So, there was only red light to be diffracted and, as they had seen with the rainbows from the flashlight, the pattern caused the light to repeat at certain intervals.   The laser was split into a grid of evenly spaced beams.

Handing over even these very low power, low grade lasers to third graders is probably something I would not do again.  One, despite warnings, I had to intervene at one point, stopping one student from shining the laser into another student’s eye at point blank range.  The second problem was in getting all of the lasers back..  one or two disappeared.  This wasn’t an issue of material loss, but I’d rather avoid the temptation and surrounding issues.

Statistics… ???

7 Dec 2011,  Patterson Elementary School, DC.

Oh no, statistics!

Allow me to say, right up front, this was my plan B.  I had hoped to have an optics plan ready for this week, but my lab tests didn’t work out.

I was trying to use gelatin (Jello) as lenses to demonstrate optics.  I used Knox ‘gelatine’ with the regular amount of water prescribed.  No sugar, no coloring.  I used a glass to form a plano-convex lens: 

The problem, it turned out, was that I can’t afford a bag full of cheap lasers.  In trying to use the gelatin lenses to form a crude telescope I learned that the optical qualities of these lenses are, well, very bad,   very, very baaad.   Additionally, the curvature of the pictured glass is waaaaay too much (I suspected this before-hand).
However, using a cheap laser pointer works pretty well.   The gelatin is fairly dispersive and yet still functions with the usual characteristics of ‘real’ optics.  Even internal reflection works well.
The neat bit is that with all that dispersion going on, you can see the path of the laser beam every step of the way…  it’s fantastic.

There are two downsides….    the cost of a bunch of dollar store laser pointers and two, working with gelatin optics leaves your fingers a bit sticky.  I’m sure the students can handle the second problem, but I buy some materials each week for these classes and I don’t have a job…..  financially that’s slightly unsound.

Anyway….   statistics…

Going in I knew this was going to be a tough sell.  We started by collecting everyone’s birth month and tallying them on the board:

JFMAMJJASOND
01030233132102
Then I demonstrated how to plot these out and called this a histogram.
Now, I didn’t run into the term ‘histogram’ until college, and these students won’t see it again for many years… however, this basic idea of graphing, I believe, can be taught at this level thus making students more comfortable with such ‘sciencey’ ideas later on in their education.

Next the torture began…
M&M’s.  
‘Fun Size’  M&M bags were distributed to each student, with a warning that they were not allowed to eat the candy.  Think about this for a second…  imagine you are 10 years old again, someone hands you a bag of M&M’s ask you to count them and says you can’t have any…   it’s a bit much, right?

The goal was fairly simple.  Count and record how many of each color were in your bag.  First, as a class, we determined all of the observed colors; Yellow, Green, Blue, Brown, Orange, & Red.  Then each student tallied the colors in their bag.

After each student had a record I should have discarded the candies…  less distraction.

Next, everyone was asked to create a graph of their data.  This is the first time these students have ever created a graph, there were some serious challenges and lots of learning at this point.  Like portions of my previous efforts, this may have been somewhat beyond the normal range of what they were expected to do in third grade but I sincerely hope to provide them a glimpse of possibilities beyond the standardized curriculum.

As simple as the exercise may sound, this was seriously intensive work for the students which took a lot of time.  I teach 2 classes, one after the other,  the first class got far enough along to talk about averages, the second didn’t .  Both classes’ results were tallied as a whole.

In case you’re wondering…   blue and orange are the most common colors found in M&M’s, brown is the least common…  and Fun Size bags range from 15 to 19 candies each.

Oh, almost forgot, after discarding all laboratory equipment and specimens, I did leave fresh candies with each teacher to do with as she pleased.  🙂

—-
One student peacefully withdrew from graphing his results.  I could see he was terribly frustrated yet, unlike some of his classmates, he did not through a tantrum, but simply had a look of frustration on his face and stopped working.  I kept circulating around the room, helping where I could.  When I came by his desk his stress was clearly evident.  I squatted down to be at his height and asked how it was going.  “I don’t wanna do this anymore”, was the reply, arms crossed, his face turned aside and lips pressed inward.  He was proud and didn’t want the others to see he needed help, but I didn’t know this …yet.  I prompted him for how to do the plotting, and that’s where he was lost.  I demonstrated how to plot some of his results..  his arms never uncrossing, he still sat away from his desk, but his eyes watched.  I demonstrated another, prompting him, asking him what to do…  he got it, but the arms never uncrossed.  I tried telling him it was all ok, but that didn’t seem to sit well.  Finally I realized that he didn’t want the others to see him being helped and left him to work on his own.  Another student was struggling, I helped, watching the arms uncross, the pencil being picked up, a graph being made…       and I learn too.

Microscopes for Third Graders

30 Nov 2011,  Patterson Elementary School, DC.

This week…  microscopes!

ReSET has a handful of well-made student microscopes, called “My First Lab Microscope Ultimate” (MFL-85)  by NYscopes.com and look similar to this: 

They are rechargeable, though the batteries on half of them have died (I don’t know how old these are and suspect they were stored without being charged).  They can still be lit with the AC adapter.  Currently they run a about $120 each.   The optics, for this price range, are excellent as is the general build quality.  The base, turret, stage, and eyepiece tube are all metal.  The intensity of the white LED  can be varied.  There is only a coarse focus, which is fine (pun) for this level of use.  The objective lenses are parafocal, or very nearly so.  The stage is translationally fixed.  It’s very nice for the money.
Anyway…

The real point of this lesson is to introduce the students to making careful observations.

We talked about parts of the microscope and went over how we would use them, before passing them out.  We also talked about how we would take turns, a serious concern with only 4 scopes and 20 students. I then explained magnification and gave some examples.

There was often trouble in trying to focus, sometimes the turret would be set between lenses, sometimes the light wasn’t on, sometimes the student would say that theirs was in focus but upon checking there would be nothing but a blur.  Odd that they were just as excited with the blur, I’m sure this should tell me something.   The rest of the class was spent looking and sketching, with Ms. Haynes and myself running around helping and settling disputes about whose turn it was.

Specimens:  I brought pond water, getting lots of really dirty gunk, baker’s yeast that I had started that morning (a tiny amount of dry yeast, a pinch of sugar, in about 1 oz of water), a flower, a leaf, a bug found on the front of my car, and a collection of bought prepared slides.

The prepared slides, the yeast, and the bug were great.  The pond water took too much care for 3rd grade.  Sketching went great too.  We were sure to label them with basic data; specimen, date, observer’s name, etc.   Trying to label the magnification used was too much.   Also, it was carefully explained that they should draw exactly what they see.

I wish I had removed the highest power objective lens from each scope.  We avoided crashing into slides pretty well, but the additional, difficult to focus (for them) lens was distracting.  With a 10x eyepiece having just a 4x and a 10x objective would have been plenty.  The scope did come with a usb camera eyepiece, but I really wanted the students to have ‘real’ experience, rather than something semi-virtual.  The camera, as is expected, is basic; 640×480, high noise.  The refresh rate isn’t too bad, focusing is tolerable.  I don’t know what magnification is on the camera-piece.  I had some issues with the included software and used Micam instead.  Here is a sample of a “mouth smear” prepared slide using the 10x objective: Again, it ain’t research grade, but it’s pretty amazing for the money.

I have wondered if a cheap ‘pocket microscope’ would be better at this grade level.  I have bought a couple of all plastic (including the lenese) 60-100x scopes that cost around 7 dollars (yes, seven) and believe they would be ok.  A slightly better scope of the same ‘pocket’ design but with glass lenses would be great.   For fourth graders it would probably depend on the class, but by 5th grade the microscope we used would be the way to go.  Of course if you are helping just 1 or 2 students then it would be good for any grade.

Lessons from the Atmosphere

16 Nov 2011,  Patterson Elementary School, DC.

The second week..

This week’s lesson was about condensation, the atmosphere, and PV=nRT (without the equation).

I started listing the 3 states of matter (yeah, yeah, there’s really 4, let it go) on the board.  I got as far as solid before students started calling out, “liquid”, “gas”.   I was impressed.  So I asked them for examples, and quizzed them on different materials.  Pudding is a stumper.

Next each table grabbed a cup of water and put ice in it, then we talked about condensation a bit.  To keep things simple and clear I kept condensation limited to water in the atmosphere.  After talking we looked at the cups, where water had condensed on the outside of the cup.
No one was impressed!

However, I asked them where the condensation came from.  This puzzled most of them.  Others answered, “from the water” or “from the ice”.  “So the water went through the cup?”, I asked and then explained what had really happened.

We talked about the atmosphere, starting with how thick or high it might be.   I asked if you could breathe in outer space: “Noooo!”, said everyone.  So then, there had to be some height at which we transitioned from atmosphere to no atmosphere.   We talked about Mt. Everest and how even the most fit climbers had trouble breathing at 5 miles above sea level.  So what guesses did they have about the atmosphere’s thickness.

There’s a bit of a problem I glossed over here.  Namely that somewhere around 6 miles up no one would have enough oxygen to survive, but where space starts is a soft number.  For space flight, 60 miles is considered to be the point where you would become an astronaut.  For most orbital analyses 100 miles is considered a minimal orbit.   For easy math I went with 100 miles,  I should have gone with 10.

Physicist routinely use simple approximations to examine possibilities and provide quick insight to how things work.  Usually this is called order of magnitude approximations or back of the envelope calculations.  It’s an extremely valuable thing to learn, especially for checking to see if your answers or ideas are in the ball park.

We talked about the size of Earth, which required a small detour into circumference and diameter.  I claimed that it’s 24,000 miles to go all the way around Earth and its diameter is 8000 miles…   close enough.  Then I tried, with questionable success, to explain idea of not being too accurate, of making a quick approximation.  I grabbed a 14″ globe and claimed it was 8″ in diameter.   Holding up a 12″ ruler I asked if this was accurate or a rough approximation…  they stumbled for a sec, but then got it.   Annnndd I introduced the concept of ratios (they did know about fractions).

Phew!  At this point I had knew I was really pushing how much material we could cover, but surprisingly there weren’t any squirmers or any acting out.  They seemed both intrigued and straining to grasp what all was going on.

With ratios in their heads I said we wanted to figured out, roughly how thick the atmosphere would be on the globe.  Guesses generally ranged between 2 to 4 inches.
So Earth is 8000 miles in diameter and the globe was 8″ in diameter.  Our guess at the atmosphere’s thickness was 100 miles.  So how thick was it on the globe?

I started with the ratios and Ms. Haynes jumped in.  It turned out that this coincided with their current math lessons perfectly.  They came up with 1/10 inch.    I found a piece of cereal box and draped it on the globe.  The atmosphere is a lot thinner than most people imagine.

Mostly as a quick fun point we then did a demo showing that air pressure works in all directions.  Over a bucket, students took a mostly full cup of water and placed a piece of paper over the top.  They quickly  inverted the cup while holding the paper in place and then ‘released’ the paper once upside down.  The paper stays in place and the water (mostly) doesn’t spill.
If you try this note that it’s a huge hit on the fun-meter.  Every student will have to try it.  Warning: you will need some large sponges to clean up spilled water.  Also, they will try to use completely soaked paper, so tell them 1 paper per try.  We used small disposable plastic or waxed cups.

After cleaning up I took an empty 2 liter soda bottle and put an empty balloon on it.  The classroom had a sink, so I ran hot water over the bottle, explaining that this would heat the air inside.   The balloon inflates (modestly).
Shocking to me, the students were thrilled by this.
So I asked, what would happen if I then ran cold water over the bottle?
“It’ll shrink” and “the balloon will get sucked into the bottle” were common answers.    ‘Nice!”, I thought.

For the last experiment…  and I can’t believe we got through all of this in an hour!    … we made clouds.   An empty 2 liter bottle with a little  (~1 cup) of hot-ish water gets pumped by a bicycle pump with a ball needle poked through a wine cork on it.   When the pressure builds up a bit the cork pops out, with a bang, and the rapid decompression causes water vapor to form in the bottle, like a cloud.  We had 2 sets of equipment.  Three students at a time are needed;  1 to hold the bottle, 1 to pump, and 1 to hold the hose near the pump nozzle.

Beware!  The pop is quite loud and will startle everyone watching, including you, no matter how many times you see it (it’s a timing thing).  I explained and exclaimed repeatedly that there would be a loud boom but it wouldn’t hurt anyone.  The students absolutely love this and everyone wants a turn pumping.  They also forget to look in the bottle for the cloud, or to clear the cloud out before trying again.  Considering how many ideas they were exposed to during this lesson, a little play time was clearly earned.

Lots of excitement, lots of ideas in this one.   🙂

Sink or Swim, Teaching Style

9 Nov 2011,  Patterson Elementary School, DC.

This week I was on my own; two classes, about 1 hour each.  That’s about 35 3rd grade Tasmanian devils swirling around with unlimited energy in a small classroom vessel.   The lesson is what I assisted with last week in the 4th grade classes, sinking and floating, aka density.

I dressed up nicely (stopping short of a tie which should only be used for weddings and funerals) , used real anti-antiperspirant, and had a cup of chamomile instead of coffee.  I gave Ms. Haynes a quick warning that this was my first time teaching elementary students and that I was a bit nervous.  She patted my shoulder and with a huge smile declared, “Don’t you worry.  I’ve got your back.”  I felt grateful and relieved.

After being introduced and unpacking the supplies, I started the “Floating and Sinking lesson” lesson, a ReSET standard.  This lesson involved using several containers of water and definitely required a stack of cleanup sponges.

The point of the lesson was to act as a demonstration of the scientific method and as an introduction to what density is.  In last weeks 4th grade lesson we actually weighed a baseball and a golfball.  The 3rd graders haven’t quite learned to read scales so I used a simple balance made of a clothes hanger with sandwich baggies attached at opposing ends.   As a class, we guessed and then measured how many golfballs equals one baseball (3).  I then gave them 150g as the weight of the baseball and asked them to find the weight of one golfball.  As it happens this lined up perfectly with their current math lessons and Ms. Haynes jumped in, taking over and giving me a much needed break.  I was sweating up a storm, my thoughts were jumbled, and I had no idea where we were going next.   Luckily I had written down a simple check list of the activities and located where we were.

Next we formed a hypothesis about what floats and what sinks in water.  They had some wild ideas but generally agreed that heavy things will sink and light things will float.  No one in either class voiced dissent, but I felt a little guilty corralling their ideas toward this conclusion.    We then placed both balls in a large container of water and made an observation…     the heavy item floated and the lighter sunk.

There were 4 tables, with 4 to 5 students at each.  They shared the equipment.   After a few steps chaos was starting to erupt over who was doing what.  It was critical to set up an order of turns; I simply numbered  around each table.

Here I tried to explain density and stumbled, wallowed, and was left facing a room full of puzzled faces.   At this point the teacher rescued me and held up two clear plastic containers holding markers.  One was nearly full, the other only had a couple of markers in it.  She explained that density was like having more stuff packed into a space.   So which of the containers had a ‘high’ density?

Next we tried floating a lacrosse ball in a cup of water and observed that it sinks.   Then, after removing the ball, we added about 1/4 cup of salt to the water.

Several of the kids in both classes had a taste of the material before being told what it was.  Sigh.  So, yes, third grade still requires purely non-toxic materials.

After adding the salt, we placed the lacrosse ball back in the water, where it floated!  Sounds simple, right?  The students went crazy over this.  After things calmed down a bit, we talked about how we had changed the density of the water.

For the final experiment we took some of the salt water and dyed it red…  well, I dyed them red.  When then took a clear cup of water and used an eyedropper to gently place some salt water along the inside of the cup.   It sinks to the bottom and forms a red layer that the students can easily see.  This experiment turned out to be underwhelming, but they seemed to get the point nonetheless.

In the end I learned that you cannot lecture to third graders and that finding great simple examples to explain you idea is critical.

Intro to Teaching

So Tuesday I emailed someone at ReSET asking to talk with them about what they do and if they’d need someone like myself.  The director responded asking if I’d like to meet at a school on Wednesday at noon.  I was nervous and really wanted to push it off for a bit, but nothing was going to change that way so I accepted.
We met at the school.  He had a clothes basket full of equipment and some 5 gallon buckets.  We talked for a bit, things seem to go well. He explained that they are invited in to a class to teach one hour a week for 6 weeks.  The school’s teacher is always present and is responsible for class management.  The volunteer should organize the lessons with the teacher, but can still choose the topic.
So after we talked he asked if I wanted to assist for a class. I agreed, while feeling nervous.
I just played the part of the assistant, helping out trouble spots, handing out materials, etc.  All went well.
The topic was an introduction to density by examining whether objects float or sink in water.
The kids really liked it.  They have so much energy and were so curious and playful.
So we did a second session as well.  I felt more comfortable and really enjoyed it.

Afterwards we talked about options; should I go and assist teachers that lack science background with their science lessons, or teach a group on my own, or shadow a couple more volunteers.   Later in the day John Meagher emailed saying that he just lost a volunteer that was covering a 3rd grade class and maybe I should consider that.

That got me thinking about lessons and what topics to try…  with lots of worry about them being truly worthwhile. I think it’s important to introduce the kids to something that they can relate to in their everyday life, not just a neat exercise they saw at school that has no direct real world use.
It’s a lot to ask for.
And maybe, given my lack of experience, it’d be better if I mostly took plans that were already in place so I could concentrate on the actual interaction with the students.  I can build better lessons later.

Www.resetonline.com

Canon LIDE 20 Scanner Disassembly

Tips on taking a Canon Canoscan LIDE 20 apart. ( In most of these pictures I have already taken the scanner apart at least once.)

PAGE_STATUS: Draft.
Should break this into parts.

I’m hoping to make a tolerable large format digital camera back for an 8×10″ field camera by modifying a Canon LIDE scanner.

The LIDE scanners are:

• very common
• supported by open-source drivers
• very cheap on the used market
• are connected by a single usb cable for both power and data
• easily powered by a netbook
• lightweight
• a long-lived series with steady incremental improvements
• lessons learned on one series apply almost directly to most others

Overview

Image by awrose via Flickr

The general idea is to strip out the optics and slap the scanner on the back of a field camera.

The sensor is a linear array with a lenslet strip positioned directly in front of it. This strip will be removed, leaving the sensor at the bottom of a deep, dark channel with a narrow field of view in the scanning direction.  As the sensor moves across the image plane, the incident rays will be occluded by the channel for a large portion of the scan.  So the channel must be widened.  This might be tricky as the sensor is glued to the structure, cannot tolerate any flexure, and should not be touched by debris.

The light source normally use to illuminate the object being scanned will need to be removed, disabled, or at least covered.

The LIDE’ scanners use the glass platen itself as support for the sensor housing.  I would like to remove the glass but there must be something to support the sensor housing.  Maybe a large rectangle can be cut out of the glass..   or two strips cut out for the guides.

The last bit of hardware is to mount the scanner onto the camera.  I’ll get everything else settled before worrying about this to much.

Software.
Even the Canon drivers will continue to work until you yank out the light source.  Once it’s out the driver may just return a scanner failure notice, or lamp failure, or calibration failure.  Afterward you’ll need to use something like SANE‘s free , open source drivers (assuming you’re using Linux).  In the end you’ll either need to some basic programming using something like the underlying bits of SANE or you can buy a copy of VueScan.  VueScan is available not only for Linux but even for more obscure systems like Mac or even Windows.  And yes, it’s worth it.

The part I haven’t started at all yet is building the image chain for this beast.  Shouldn’t be too hard.

Imaging Expectations

It’s gonna be noisy.  Anything in the scene that moves will be distorted (linear array).  B&W only.  No idea where the sensor cuts off…  ~360nm to ??~1100nm??… maybe 900.. dunno.   Unsure if integration time varies with scanning settings or if it’s just fixed.  Scan times for older models ~1min, newer models ~8sec.   Output image: TIF up to 19000×26000 pixels, at ?10bit.   Unsure about bitdepth..  Canon claims 16b, but I’ll call BS on that.  It’ll depend on the noise. Wouldn’t be surprised if it was only 6 or 7 bit in the end.

Begin disassembly

Here’s the scanner, minus the cover. The cover is easy to remove by simply flexing the hinge a bit.    -v2  Well, on the LIDE 25 it took a lot more pressure than the LIDE 20.

Remove platen retainers

A plastic retainer runs down each long side of the platen. They stop the platen from sliding forward which would free it. There are no screws. The plastic strips are held in place with tape along most of their length.

Begin at the front of the scanner and pry up the ‘ovals’.

You can see coming at the sides of the ovals is a good place to work. (I initially started at the very end.)

Pull gently while slipping something underneath to separate the tape from the plastic. As I’m planning on removing the platen permanently, scratches were not a concern.

One strip off, one to go.
With both retaining strips gone, the platen will slide back with moderate pressure. Once back, the platen can be removed entirely.

Sensor and platform details

Move the platform toward the middle of the scanner. I did this by pulling the cable mid-scan. Ugly, but I haven’t had any problems.  Notice the ‘rod’ and the ‘string’.

WARNING: There are two, free-floating plastic glides on the top of the platform. Collect these now.

Drive string

The ‘string’ is freed by unlocking the endpiece where the spring sits. On the bottom of the scanner (be sure not to turn the scanner over), next to the platform lock, you’ll see a small, round hole. Insert say a small screw driver and push gently to allow this ‘string lock’ to be freed. While pushing the screw driver, slide the string lock free.
You can carefully flip the platform over to see how the string runs through the gears. Separate the string from the platform. Be sure not to kink the string.

Sensor package removal

WARNING: There is a small spring underneath the sensor package. It will come free as you remove the package.

The sensor package pivots on a hinge on the platform. It can be worked free with very little pressure as it slides to unlock when slightly elevated.

Sensor detail

Here you can see the light guide and the lenslet strip. In this picture the light guide is just above the screwdriver tip and the lenslet strip is one of the black horizontal pieces.  There’s a better shot of the lenslet placement a few pics below.

Here is the LED used to illuminate objects during scans. It seemed to be just butted against the light guide without adhesive.

Light guide removal

This is easier than I had expected. I gave each of the attachment points a gentle prying. Not enough to really see any movement. Then started prying at the end opposite the LED, switching to just pulling with my fingers as soon as I could get a hold.

Lenslet removal

Like the light guide, the lenslet strip is easy to pry out.  The strip will be discarded, the only real concern is with possible damaging the sensor directly below while removing the strip.

WARNING: There is nothing protecting the sensor but this lenslet strip.
A note on cleaning the sensor… Don’t worry about a bit of dust getting on the linear array. But do make sure that your tools and particles of plastic created while working keep clear of the sensor. If you wish to clean the sensor use air. A small squeeze bulb is perfect. Do NOT use those old cans of compressed “air” from back in the film camera days. They contain chemicals that can contaminate the senor’s silicon.
Ha!  That turned out to be a non-issue.  The sensor is embedded within some form of clear plastic or something similar.  (pics and description coming soon)

 

 

LIDE 25

 

Related articles

• VueScan 9 Versatile Scanner Software: Better than Ever, Charles W. Moore, Miscellaneous Ramblings (lowendmac.com)