The OTHER major problem with TFA

… as Peter Greene explains, is that it takes untrained newbies with TWO WHOLE YEARS (snicker) of classroom experience and claims that they are now ready to run an entire school system.

He explains:

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Teach for America: The Other Big Problem

Posted: 03 Jun 2019 10:31 AM PDT

Teach for America’s most famously flawed premise is well known– five weeks of training makes you qualified to teach in a classroom. It’s an absurd premise that has been criticized and lampooned widely. It is followed closely in infamy by the notion that two years in a classroom are about providing the TFAer with an “experience,” or a resume-builder so they have a better shot at that law or MBA program they’re applying to. That premise has also been widely criticized.

There’s another TFA premise that is less remarked on but is perhaps, in the long run, far worse. From the TFA website:

To change our country’s education system, we need leaders challenging conventional wisdom and the status quo, working for the long term from both inside and outside the school system. Once you become an alum of TFA, you’ll bring an invaluable perspective to any career field in working to create opportunity for students and communities nationwide.

This is the other TFA premise– that two years in a classroom makes you qualified to run a school, or a school district, or a state education department. Two years in a classroom makes you qualified to be an education policy leader.

This is nuts.

First of all, two years in a classroom is nothing. For most folks it takes five to seven years to really get on your feet as a classroom teacher, to really have a solid sense of what you’re doing (and you will never, ever, reach a point at which you don’t have much more to learn about the work). The beginning two years are a challenge for anyone, and in the case of TFA, we’re talking about the first two years of a person who only prepped for the job for five weeks! So they are starting out behind the average traditional new teacher. And if they are teaching in, say, a charter where they are surrounded primarily by other newbies, or being coached and led by TFA staff who are alumni who only have two years in the classroom– well, the problems just compound. This is not the blind leading the blind– this is the blind being led down a cliffside path into the Grand Canyon by a blind guide who is riding on a disabled Roombah.

Second, I will totally give a large number of TFAers in the classroom credit for good intentions. Yes, some have joined up specifically to beef up their grad school application or give themselves an “experience,” but I believe that a significant number of TFAers entered the classroom hoping just what most traditional teachers hope– that they could do good and make a corner of the world a little better.

But what the heck has to be going on in your head if, after two years of classroom teaching, you’re thinking, “Yeah, I could totally run an entire school” or “I bet I could really fix this district if I were in charge” or “The education in this state would be so awesome if they put me in charge.” I told almost every student teacher I worked with, every first-year teacher I ever mentored, “It’s okay. If you don’t cry at some point during this year, that just means you don’t fully understand the situation.” How bad does your grasp have to be, how deep in the grip of Dunning-Kruger do you have to be, to look at your tiny little sliver of just-getting-your-feet-wet experience and think that you are ready to run the show? This is a level of delusion I find truly scary.

And yet. Part of TFA’s goal has always been to create the educational leaders who could turn the educational ship toward the course that their fully-amateur navigators had charted.

They’ve been successful. As a reminder, look at some of the alumni notables listed on TFA’s Wikipedia page:

Mike Feinberg (Houston ’92), KIPP Co-founder

Mike Johnston (Mississippi Delta ’97), Colorado state senator

Kevin Huffman (Houston ’92), Tennessee State Education Commissioner, April 2011 to January 2015

Michelle Rhee (Baltimore ’92), Former Chancellor of District of Columbia Public Schools and founder of The New Teacher Project and StudentsFirst

Alec Ross (Baltimore ’94), Senior Adviser for Innovation for Secretary of State Hillary Clinton

John C. White (2010), Louisiana state superintendent of education since 2012

But there are plenty of lower-profile TFA alums out there. For instance, go to LittleSis and look through just some of the Teach for America alumni connections (while you’re at it, look at who funds and runs TFA). There’s a director of industry learning at McKinsey, a vice-president at the Boston Foundation, a guy who worked for NYC’s ed department and now works in charter school development, the chief academic officer at National Heritage Academies, a partner at Learn Capital. TFA’s own alumni page includes folks now working with The Mind Trust, KIPP, and the Walton Family Foundation.

Or consider the TFA Capitol Hill Fellows Program, one of the TFA initiatives that was designed to make sure that TFA has a voice in federal education policy.

The numbers are– well, if we look at just, say, TFA in Memphis, we find there are 410 TFA alumni in town. 250 are in a classroom, 24 are school leaders, and 6 lead a school system. With two whole years in a classroom under their belts, they lead an entire system.

TFA’s own national alum figures show that 34% are in a classroom and 84% “work in education or in fields that impact low-income communities”  which works out to half the TFAers believing that their two years in a low-income classroom qualifies them to do education or community work.

You can drill down and find the specific pictures anywhere in the country. What started me thinking about this was Lorain, Ohio, a story I’ve been following that involves a state-appointed all-powerful CEO. This is a guy with two years in a classroom, and yet he has since that time launched a charter school and served as a consultant for a major urban district before coming to Lorain to run the whole system. And he’s hired “turnaround principals” who are also TFA products, who are taking over administration of entire buildings based on their two years as a beginning teacher in a classroom. And all of these folks don’t need anybody to tell them anything because they are education experts.

This is nuts.

TFA’s drive to plant its seeds everywhere is one persistent symptom of the early days of modern reform, back before when Reformsters figured out that badmouthing public school teachers was counterproductive. After all– if a two-year classroom veteran makes a good principal or superintendent or state commissioner, why haven’t more places reached out to recruit ten or fifteen or twenty year veterans of public school classrooms for leadership or policy positions (yes, teachers are allowed to rise to principal or superintendent positions, but the state capitol doesn’t call very often). If two years in the classroom make you an education expert, then twenty years ought to make you a genius. Except, of course…

TFA education policy leaders and administrators are an expression of that reform idea that we don’t just need a parallel system of education, but we need to reject all educational expertise that already exists. It’s not that hard– any person with an ivy league degree could figure out not only how to teach, but how to run a school, a district, or a state. TFA, the Broad Academy, other alternative systems deliberately reject the educational expertise that exists and attempt to build their alternative system from scratch, trusting that their own amateur-hour wisdom renders all that came before moot.

“You had five weeks of training, so now you’re ready to take over a classroom,” was silly.

“I put in two years in a classroom, so now I’m ready to take over the whole operation,” is a higher level of delusion, and yet these deluded soldiers continue to make inroads like weeds, coming first through concrete cracked open for them by their rich and powerful patrons, and then, once through, bringing more of their crew to join them.

A light-weight mirror cover for tight quarters

I built a Krueger & Berry style Dobsonian strut Mount telescope a few years ago around a 12.5″ full thickness mirror that I swapped for. The only problem was that even though the mirror sits in a box, said box has no bottom; hence, it’s no problem for all sorts of dust, pollen, and god bows what else to land on the mirror; obviously, the more Schmutz that gathers, harder it is to see stars, planets, galaxies and so on.

When I inspected the mirror last week before a little neighborhood star party at the home of another telescope maker who lives North of Baltimore, The mirror was so disgusting that I removed the mirror from its box and cell and washed it off carefully in a laundry tub that I first washed out. (Recipe: wash tub, wash hands, rinse both, put mirror under tap, rinse off as much as possible just with its flow, then fill tub part way with lukewarm water, add a fragrance-free detergent, swirl that around with fingers, then start running your clean, wet, slightly soapy water gently around the mirror. Use fingernails to pick off anything you feel. Respect. Turn mirror. Rinse. Repeat. Then rinse a bunch more. Remove mirror from water, put it on a soft clean towel that’s not hot fabric softener, on its edge; use a clean washcloth to pat dry if needed on the front.

It worked great.

Btw I’m willing to do this because I can recoat it whenever I want in our club’s alumunizer.

But taking it out & putting it back in is a PITA, and dangerous, to boot — good chances of dropping it coming out or going back in!

So I designed an inner mirror cover. It took a lot of iterations, using measurement, a geometry drawing program, numerous full sized models made from corrugated boxes we were going to recycle, and hot glue – just for the five or six cardboard prototypes. Then I used some thin lauan plywood and some reinforcements carved by band saw from thicker plywood, and some plastic sheet, pink duct tape, and colored thumbtacks.

Here are photos of the result;

Fixing Basic Flaws in Photosynthesis: A Good Idea or Worse Than Frankenstein’s Monster?

I just read an article in New Statesman saying that some molecular biologists had succeeded in fixing a basic flaw in the process of photosynthesis.

Photosynthesis isn’t very efficient — only roughly 3% iirc.

Apparently plants have a tendency to latch onto O2 molecules instead of CO2 molecules, producing toxins instead of sugars and free oxygen, slowing plant growth by a lot. Since all green plants use the exact same process of photosynthesis, no plant has an evolutionary advantage.

The link is here.

The scientists quoted claim to have figured out a way to get tobacco plants to avoid treating oxygen like carbon dioxide, and that the tobacco plants then produced 40% more biomass.

If their claim is true (I’m skeptical until I read of others replicating their work) then it might very well happen that there are enormous, unintended side effects on the plant itself that we can only guess at. So far, almost all of the “Green Revolution” plant changes have, from what I’ve read recently, not produced much change in output per plant or per hectare. (Fertilizers are a different matter…)

If this experiment is in fact successful, then one worry would be that the CRISPR’d genes (or the plants themselves) would escape from the planted fields into the wild — where they would out-grow, and hence out-compete other plants that didn’t have this photosynthetic “fix”. Who knows what would happen? I don’t but I think the effects could well be catastrophic.

This is potentially an enormous change. Better be very, very cautious about this!!!

“ut even if this trait does spread beyond farms it’s unlikely to cause serious problems, says plant geneticist Maureen Hanson of Cornell University.

“Enhanced growth of a weedy species is not likely to disturb ecology as much as we already disturb it through the environmental effects of traditional agriculture,” she says.”

I’m not so sure about that.

Videos on Telescope Making from Gordon Waite

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Gordon Waite is a commercial telescope maker who has made a number of very useful YouTube videos on his grinding, polishing, parabolizing, and testing procedures. I thought some of my readers might be interested in viewing them. The link is here, or else you can copy and paste this:

https://www.youtube.com/user/GordonWaite/videos

First Light on an 8” Scope and 1/4 Lambda on a 6” Mirror — All in One Night!

Tonight, Jim K essentially completed his 8″ telescope by putting in the primary mirror, positioning it correctly in the tube by focusing it on the Moon, and achieved FIRST LIGHT!

He also put on the Telrad finderscope and used it to aim the scope accurately on the star Capella with no difficulty at all. I did a brief star-test on that star and found that the scope passed with flying colors! Jim started grinding the mirrors back in the 1970s, put it aside, and brought it to us for help in doing the final polishing, figuring, aluminizing, and designing and constructing the telescope. It looks great and works well, too!

In addition, Pratik T may have finished figuring his 6″ f/8 mirror that he’s been working on. Using the Foucault/Couder knife-edge test measurements I made, the program FigureXP declared it to be 1/4 lambda error on the wavefront. This may be good enough, but more testing would be a good idea, later on.

We are closed all of next week for the holiday.

Some Progress – AT LAST! – With Figuring the 16.5″ f/4.5 Thin Mirror That Headlines This Blog

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I have been wrestling with this mirror for YEARS. It’s not been easy at all. The blank is only about twice the diameter of an 8″ mirror, but the project is easily 10 times as hard as doing an 8-incher. (Yes, it’s the one in the photo heading this blog!)

Recently I’ve been trying to figure it using a polishing/grinding machine fabricated by the late Bob Bolster (who modeled his after the machine that George Ritchey invented for the celebrated 60″ mirror at Mount Wilson over a century ago). That’s been a learning exercise, as I had to learn by trial and error what the machine can and cannot do, and what strokes produce what effects. The texts and videos I have seen on figuring such a large mirror with a machine have not really been very helpful, so it’s mostly been trial and error.

My best results right now seem to come from using an 8″ pitch tool on a metal backing, with a 15 pound lead weight, employing long, somewhat-oval strokes approximately tangential to the 50% zone. The edge of the tool goes about 5 cm over the edge of the blank.

This little movie shows the best ronchigrams I have ever produced with this mirror, after nearly 6 hours of near-continuous work and testing. Take a look:

And compare that to how it used to look back in September:

 

Also compare that to the theoretically perfect computed ronchigrams from Mel Bartels’ website:

perfect theoretical ronchigrams for guy's 42 cm mirror

Part of the reason this mirror has taken so long is that after grinding and polishing by hand some years ago, I finally did a proper check for strain, and discovered that it had some pretty serious strain. I ended up shipping it out to someone in Taos, New Mexico who annealed it – but that changed the figure of the mirror so much that I had to go back to fine grinding (all the way back to 120 or 220 grit, I think), and then re-polishing, all by hand. I tried to do all of that, and figuring of the mirror, at one of the Delmarva Mirror Making Marathons. It was just too much for my back — along with digging drainage ditches at Hopewell Observatory, I ended up in a serious amount of pain and required serious physical therapy (but fortunately, no crutches), so this project went back into storage for a long, long time.

Recently I’ve tried more work by hand and by machine. Unfortunately, when I do work by hand, it seems that almost no matter how carefully I polish, I cause astigmatism (which I am defining as the mirror simply not being a figure of rotation) which I can see at the testing stand as Ronchi lines that are not symmetrical around a horizontal line of reflection. (If a Ronchi grating produces lines that look a bit line the capital letters N, S, o Z, you have astigmatism quite badly. If astigmatism is there, those dreaded curves show up best when your grating is very close to the center of curvature (or center of confusion) of the central zone.

Using this machine means controlling or guessing at a LOT of variables:

  1. length of the first crank;
  2. length (positive or negative) of the second crank;
  3. position of the slide;
  4. diameter of the pitch lap;
  5. composition of the pitch;
  6. shape into which the pitch lap has been carved;
  7. amount of time that the lap was pressed against the lap;
  8. whether that was a hot press or a warm press or a cold press;
  9. amount of weight pushing down on the lap;
  10. type of polishing agent being used;
  11. thickness or dilution of polishing agent;
  12. temperature and humidity of the room;
  13. whether the settings are all kept the same or are allowed to blend into one another (eg by moving the slide);
  14. time spent on any one setup with the previous eleven or more variables;

Here is a sketch of how this works

bolster's ritchey-like machine

Major Moving Day at Hopewell Observatory

Yesterday we moved a lot of heavy metal and glass to temporary quarters so that we can mount a modern, heavy-duty Astro-Physics 1600GTO mount on one of our piers.

One of our founders, Bob Bolster, had built with his own hands a very unusual 30-cm Wright-Newtonian telescope and an equatorial mount on a permanent pier. Unfortunately, the drive stopped working and he was unable to get it back into working order before he died. So yesterday we removed it from its mount – and it took five of us with a 2-ton chain hoist, lifting straps, and a custom-built cart to winch it out of the observatory and into our operations cabin.

We all had fun doing it, nobody got injured, nothing got damaged, and the night that followed was the clearest one I’ve seen in a long time! Great open clusters in Cygnus!

I attach some videos and photos of the move.

By the way, that large disk of optical glass you see in the last few photos is for sale. We aren’t sure what type of glass it is, but you can find details here at Cloudy Nights or Astromart. It is 55 cm across, 83 mm thick, and we measured its weight as 59 kg (130 lbs). We calculate its density as 2.99 g/cm^3, and the nearest match in the Schott catalog is N-SF64 which has that exact density, but N-KZFS4 and P-SK57 are close as well (3.00 and 3.01, respectively). It’s definitely way too dense for Borofloat, Zerodur, or any other borosilicate glasses. The glass known as BAK-4 has density 3.05, which I don’t think is close enough, since there are several others between 3.00 and 3.05.  For comparison, the relatively inexpensive optical glass known as BK-7 has a density of 2.5.

We are asking $950 for the blank. If you were to order a brand-new one from any optical glass company it would cost you much, much more!

Why Not Show Students the Beauty of Math?

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When I taught math, I tried to get students to see both the usefulness and beauty of whatever topic we were discussing. The most beautiful mathematical objects I know of are the Mandelbrot and Julia sets, which in my opinion should be brought up whenever one is studying imaginary and complex numbers.

To illustrate what I mean, here are some blown up pieces of the Mandelbrot set. Below,  I’ll explain the very simple algebra that goes into making it.

 

I made these images using an app called FastFractal on my iPhone. The math goes like this:

Normally, you can’t take the square root of a negative number. But let’s pretend that you can, and that the square root of negative one is the imaginary number i. So the square root of -16 is 4i. Furthermore, we can invent complex numbers that have a real part like 2, or 3.1416, or -25/17, or anything else, and an imaginary part like 3i or -0.25i. So 2-3i is a complex number.

Ok so far?

We can add, subtract, multiply and divide real, imaginary and complex numbers if we want, just remembering that we need to add and subtract like terms, so 4+3i cannot be simplified to 7i; it’s already as simple as it gets. Remember that i multiplied by i gives you negative one!

Interesting fact: if you multiply a complex number (say, 4+3i) by its conjugate (namely 4-3i) you get a strictly REAL answer: 25! (Try it, using FOIL if you need to, and remember that i*i=-1!)

Furthermore, let us now pretend that we can place complex numbers on something that looks just like the familiar x-y coordinate plane, only now the x-axis becomes the real axis and the y-axis becomes the imaginary axis. So our complex number 4+3i is located where the Cartesian point (4, 3) would be.

Ok — but what’s the connection to those pretty pictures?

It’s coming, I promise!

Here’s the connection: take any point on the complex plane, in other words, any complex number you wish. Call it z. Then:

(1) Square it.

(2) Add the original complex number z to that result.

(3) See how far the result is from the origin.

(4) Repeat steps 1 – 3 a whole lot of times, always adding the original z.

One of two things will happen:

(A) your result stays close to the origin, OR

(B) it will go far, far away from the origin.

If it stays close to the origin, color the original point black.

If it gets far away, pick some other color.

Then repeat steps 1-4 for the point “right next” to your original complex point z. (Obviously, the phrase “right next to” depends on the scale you are using for your graph, but you probably want fine coverage.)

When you are done, print your picture!

If we start with 4+3i, after one round I get 11+27i. After two rounds I get -604 + 597i, which is very far from the origin, so I’m going to stop here and color it blue. I’ll also decide that every time a result gets into the hundreds after merely two rounds, that point will also be blue.

Now let’s try a complex point much closer to the origin: how about 0.2+0.4i? I tried that a bunch of times and the result seems to converge on about 0.024+0.420i — so I’ll color that point black.

This whole process would of course be very, very tedious to do by hand, but it’s pretty easy to program a graphing calculator to do this for you.

When Benoit Mandelbrot and others first did this set of computations in 1978-1980, and printed the results, they were amazed at its complexity and strange beauty: the border between the points we color black and those we color otherwise is unbelievably complicated, even when you zoom in really, really close. Who woulda thunk that a simple operation with complex numbers, that any high school student in Algebra 2 can do and perform, could produce something so beautiful and weird?

So, why not take a little time in Algebra 2 and have students explore the Mandelbrot set and it’s sister the Julia set? They might just get the idea that math is beautiful!!!

IMG_1735

How Thick Are the Coatings on the Mirrors We Aluminize?

At the NCA ATM class at the CCCC, we are the fortunate inheritors of a 1960s-era vacuum chamber and aluminizer that was twice given away as surplus (first by the Federal Government or US military, and then later by American University), but which still works.

Much of the credit should be given to Dr. Bill Pala, who snagged it for AU from the US surplus system; the late Bob Bolster and Jerry Schnall, who together ran it for a long time; Dr. John Hryniewicz; Alan Tarica; and several others whose names unforotunately escape me at the moment but who have given excellent advice on repair and maintenance and even provided replacement parts.

Here are four photos of the rig, followed by two of our finished mirrors.

IMG_0064

032

The question came up: (1) how thick are the coatings we generally put on our mirrors, and (2) how efficient is it — that is, of the aluminum that we vaporize, how much of it actually lands on the mirror?

Thankfully, John H actually measured how thick the coatings are as we coated a mirror. He found that the average thickness is about 93.4 nanometers (billionths of a meter, or thousandths of a micrometer, or millionths of a millimeter), and that the coatings looked like this when blown up sufficiently: ”

 I have attached some scanning electron micrographs of the top of the film.  The grain structure is very fine, you can compare the size with the scale bar at the bottom that shows you the length of the total bar (10 ticks, between each pair of ticks is 1/10 of that number).  There are some particles or perhaps larger grains on top.  They are still very submicron, a couple of tenths at most.

The way the mirrors get coated is basically three steps:

(1) We get the mirror very, very clean, using both with a special detergent (Alconox) bbefore it goes into the vacuum chamber, and high-energy electron bombardment while the pumps are working;

(2) We get the pressure in the chamber very, very low, so that there are relatively few air molecules or atoms between a coiled tungsten filament and the mirror. (We get the pressure down to somewhere in the range of 7*10^-5 to 4*10^-4 Torr, depending on which gauge you believe. This is quite low indeed – roughly the air pressure at the altitude of the International Space Station; this is needed so that the aluminum atoms won’t tend to bounce of the molecules of nitrogen and oxygen and lose their energy.

(3) We melt, and then boil off, a small quantity of pure aluminum from the filament, which goes off in all directions, fairly evenly; the Al atoms that happen to be going in the right direction ashere to the mirror. There, they form a very even, reflective layer.

You may wonder, how do we prevent this layer of aluminum from oxidizing once it comes back into contact with the normal atmosphere? Answer: we don’t. Aluminum oxide is the main component of rubies, sapphires, and corundum, which are very hard. Since the stuff we deposit is relatively pure, it doesn’t have the red or blue color of those pretty and precious gems, and it is transparent, so it forms a hard, transparent, protective layer all by itself. If your coating tarnishes or gets extremely dirty, the aluminum-and-gunk layer is pretty easy to remove with a little bit of hydrochloric acid mixed with copper sulfate. Then you clean it off and re-aluminize.

(Yes, commercial labs do overcoat their mirrors with stuff like Silicon Monoxide and Silicon Dioxide (aka quartz), but we haven’t collectively figured out how to do that with our minimal budget.)

So, again: how efficient is it? What percentage of the atoms of aluminum headed to the mirror, actually adhere to the mirror?

To answer this, it helps to pretend that the filament is at the center of an imaginary sphere, shown below, and that the mirror (facing down, towards the mirror) happens to be at the top of this sphere. Recall that to a good approximation, the aluminum that evaporates off of the coil goes in all directions, i.e., it coats this entire imaginary sphere equally – or it would, if there wasn’t all sorts of pipes and wires and glass bell jars in the way.

The filament and aluminum is located at the center of this sphere.

I measured the distance from the filament to the mirror, and found that it’s just about 20 inches, or roughly 500 millimeters. Archimedes figured out long ago that the surface area of a sphere is equal to four times the area of any circle contained in the sphere, or 4*pi*r^2 in our current notation. So that imaginary sphere, on which the aluminum is deposited, has an area of about 3.1 or 3.2 million square millimeters.

imaginary sphere for aluminization

We currently use slugs of aluminum that are about 15 mm long (give or take a couple of mm) and cut (not at right angles, because the pliers won’t do that) from wire with a diameter of 5 mm (radius 2.5 mm). If we pretend the slugs are cylinders then the math is much easier: we can use the formula pi*r^2*h to get a volume of about 295 cubic millimeters, and we will pretend that all of the aluminum boils off (and none of it sticks like glue to the tungsten) and goes equally in all directions. (Probably not the case, but in practice it doesn’t seem to matter much.)

Now if we divide the 295 mm^3 of aluminum by the total surface area, 3.2 million mm^2, we get the average thickness. I get a result of about 9.1*10^-5 mm, which converts to 91 nanometers. Which is very close to the result that John H found.

On the other hand, most of that aluminum is wasted, because it’s NOT aimed at the mirror. If you have an 8-inch diameter mirror (about 20 cm diameter or 100 mm radius), its area is 10,000*pi square millimeters, or about 31,000 mm^2 – and that’s only one percent of the area of the entire imaginary sphere.

Oh, well, aluminum wire is quite cheap.