Great day

We've had ONE day with lenses and already we're putting things together. I started the day by having each group demonstrate something cool/interesting/perplexing they had seen, and then - if they could - diagram what was going on. The conversation on why rays bend in a lens is going to be worth looking into more carefully, so I'm blogging what I remember from the day...


Group 1. Amy had this idea that our retina is kind of like those "executive toys" (why are they called that?) pin art things -- and we build up images from these tiny dots of cones/rods. It's a crazy but true idea that just seems so obvious to me now -- it was nice to have a student articulate it and be excited by her idea (and now crazier to me is that we perceive "wholeness" at all!).  I gave them some tips on things to notice and explain - mainly having to do with our peripheral vision. They think that the middle of our eye - the macula - has closely spaced pins while the periphery is further apart and yet, they note, we don't see "holes" in our vision - which they think must be a problem the brain solves.

On to Group 2. They were taking a cut-out shape, shining a light through it, and then through a magnifying glass. As they moved the glass back and forth, the image of the cut-out shape would "flip" - the point of "flip," they note, is like a pinhole -  the rays are all crossing. They sketched it like rays crossing IN the lens and then again outside the lens - so it was kind of iffy.

On to Group 3 - Here they were using lasers and had two lasers - one red & one blue - held side-by-side so the rays are parallel.  If you move the screen back and forth, you first see the red-on-right, blue-on-left - then they cross. It's consistent with group 2, but the diagram was more clear. Two rays enter the lens (from the right), on the other side they exit aimed towards one another, and then they cross. Very clear.  Awesome. They've also brought in jell-o because it reminds them of the vitreous humor and diagram how that travels through the jell-o - it's offset from where it would be without the jell-o. They compare it to how a straw looks "bent" in water -- though they're far from the explanation, these connections are cool...

(as I'm typing I'm looking back at the video and realizing it's only 25 minutes of video. This should be 2 hours. ARRGH!)

Group 4 had been interested in the humor too, so had been looking at laser light in cups of water - then (at my silly suggestion) added a bit of milk from their latte to make the lasers more visible. Instead what they noticed was that the blue laser light was scattered, the red wasn't. I'm pretty sure this is Mie scattering they're seeing... they had ideas about how the humor might protect the eye from blue rays - but mostly they were just perplexed by a phenomenon pretty unrelated to the eye. I would let them continue with that, but with 2 weeks left I thought better of it and clued them in.

Still, they showed the demo, and it's different in jell-o than in milk (see above - yellow jell-o, green transmitted, blue goes nowhere).

Group 5 had been modeling the eye's parts as three separate lens-like elements: cornea, humor and lens. They took three lenses in a row and could see images in them. It's upside-down, as we've heard images are ... no good sketches from this group, though.

Group 6, however, had taken three different lenses and played around (essentially) with focal length by imaging a flashlight.  Coincidentally, the small lens was the short focal length, so that's throwing them off - One of the perplexing things they note is that it seems like the lens-retina distance is fixed, so shouldn't dilating our pupil change the focal length? (this is b/c they think that diameter of lens affects the focal length) -

I highlight differences in how groups 2, 4, and 6 are drawing the lens and *thought* that group 4 had shown rays inside the lens (they only showed them in the jello). So in pointing this out, D. has an idea - he'd read that light travels slowly in a lens, so maybe that's what's doing the bending. In fact, I think he read more than he let on -- he has an idea that it's like a car driving into mud and one side hits first and slows and so the car pivots.  (The Khan Academy video on lenses says exactly this.) What's nice about this way that he brought it up, though, was that others could challenge it -- he just tossed it out as an idea as opposed to a fact he looked up, and M. said she thought a car was the wrong analogy - rays are like motorcycles, not cars! I *love* this. K. says something similar - that a car would pivot, but the rays would shatter a little - or separate. But then they think maybe a motorcycle would pivot too, a little? - and the mechanism is consistent with our observations... direct-hit rays don't bend.  This is going back-and-forth for a while so I paused and asked the 0 - 5 question (show with fingers if you're following the debate)- folks were either 0's or 5's - so I recapped on the board and offered Carlie's rowing analogy from a few semesters ago.

Anyway, I was beyond impressed at how far they had gotten in a day, the range of ideas they brought up, they way they were connecting observations and theories, the precision that a few groups were using.

PERC ideas

Maybe everyone who has organized a PERC had similar ideas, but I really want to do something cool with the PERC! - particularly things that relate to the idea of affect (not that these all do).  Some ideas, and I'm curious how these sound to my readers:

1. Poster session clustering:
use some software (a friend told me what I'd need to do...) to come up with a range of cool ways to cluster papers: keywords, citations, lineage, content-area. What I'm really picturing is an interactive online tool - a network diagram that you can organize by citations or keywords or whatever. So you can see how posters might cluster based on different kinds of things.  We'll probably cluster by a loose topic/content - but you could visualize other ways of clustering and find the posters that might be similar to your own, if far away location-wise.

2. Journal club:
Ask one or two of the speakers to recommend a paper of theirs that they would like to discuss, and then organize a group to meet over lunch or dinner to discuss the article. Or perhaps set this up so that it's a group that reads several papers - one from each speaker - in advance of the conference and then set up meetings with the authors while at the conference.

3. First-timers:
Other conferences organize meet-n-greet for first-time attendees. Maybe we're small enough that we don't need to do this - but I bet that's not true.

4. Twitter:
There are some strongly pro and strongly anti twitter-at-conferences folks. But there's cool stuff you can do with twitter - ask questions, "see" other talks that you didn't, alert others to a cool poster they should see, send out tweets of where to meet up and when, etc.  Other research communities I know about through colleagues (digital literacies and data visualization) are reallllly active on twitter and it works well.

5. Blogger meet-ups?
Blogging (periodically - when I'm really "on") changes my research life. Seems like we could do something with that.

6. Informal spaces
Not sure what I mean by that just yet.

Imagining a TE paper...

I'm imagining a paper on TE that really highlights for physics faculty the drudgery of what goes on in most intro physics labs, and compares this to Inquiry and then presents some ideas about the differences between the two classes. I have more ideas about where it goes from here... something perhaps for PERC with Brian?

“Right now, our group is working on the idea of how glasses and contacts change the shape of your cornea to balance out a person's misshapen cornea. We thought we could explain it by explaining that people with near-sighted vision need glasses with thicker glass on the sides and that people with far-sighted vision need glasses with thicker glass in the center. However, we only knew what near-sighted glasses looked like. We didn't know what far-sighted glasses (e.g., reading glasses) looked like. When I was at Walgreen’s the other day, I saw some reading glasses and decided to investigate. And sure enough, the glasses were thicker in the center and as the intensity of the prescription increased, so did the thickness of the center. I was so proud of our group to turn out correct!”  - Student, May 2011

In one unit of the course Scientific Inquiry, students (primarily future elementary teachers) begin by dissecting cow eyes and, through reading case studies regarding vision and designing their own experiments, work to describe the roles the various parts of the eye play in vision.  There is no textbook or lab manual, and students struggle to describe how it is that a lens, cornea or the internal humors bend light rays so that they “reconvene” at a particular point. One group may be examining lenses more generally, another group is trying to describe what we come to call the “fry an ant” spot, a third group puzzles over why it is that different animals have differently-shaped pupils. They use everyday materials: laser pointers, chalk dust, water, magnifying glasses, and shapes cut in tinfoil. They begin to discuss phrases like “the curvier the lens, the more light bends,” and, as they discuss between groups, students work to refine these ideas to precise descriptions of the refraction of light rays. They wonder whether the thickness or the curvature of the lens is the important factor, or simply the angle at which the ray strikes the lens. One student comments “all curves seem flat if you’re small enough” - like an ant on the surface of the earth - so perhaps what matters is not curvature so much as the angle of incidence. Over time, these conversations lead towards ideas about how the shape of a lens creates a focused image on the retina. One group extends this to examine their own glasses— they try to figure out why glasses don’t work if worn “backwards” and how the thickness of glasses should change for near- v. far-sighted vision. It is this group that begins to construct hypotheses that are finally verified at Walgreen’s in the quote above.

In the physics labs across the creek, science majors are enrolled in introductory physics and are doing a lab on Snell’s Law - the very law the students in the Inquiry class are moving towards constructing. They aim large HeNe lasers at the center of the flat edge of an acrylic semicircle from Pasco. The semicircle is used so that a ray will refract upon entering but not upon exiting the medium, making  later calculations easier to perform. Students measure the angle of incidence and angle of refraction for a range of incident angles, as described by the lab manual.  They choose how to record and plot the data, and are asked to use their plots to establish the index of refraction of acrylic and “prove” that two angles are related via a simple formula: Snell’s Law.  Their work is measured on two criteria: whether their value for n matches the accepted value within the limits of the uncertainty of their measurements and if they can explain how their graph is consistent with Snell’s Law.

The elementary education majors never arrive at Snell’s Law. They develop the less-quantitative notion that the more that light is “grazing” a surface, the more it will bend upon entering, and light that hits “straight on” does not bend at all. They do not relate this relationship to the speed of light in various media (the n of Snell’s Law) or have an explanation for why the relationship is what it is— the finding is purely phenomenological. When we look at these students through the usual classroom assessments of physics: do they know and can they apply the laws of physics, the elementary education majors - already behind the science majors in terms of scientific literacy - are falling farther behind their peers across the creek.

For the science majors, however, surveys reveal that they are not particularly excited by their findings. They rarely seek out opportunities to apply ideas from class to everyday phenomena; when friends and family ask about school, they do not talk about Snell’s Law; they do not report seeing examples of Snell’s Law in everyday places or perform experiments on their own time to extend their understanding of the phenomenon. This is not particularly surprising to most physics faculty, who are routinely disappointed by their students’ ennui (and who are perhaps underwhelmed by Snell's Law). But for the elementary education majors, their survey responses are markedly different:

• “My roommate has said that although the pinhole [camera] is interesting and how the eye works, she is tired of me bringing it up each time after [I] have class.”
• “My friends are actually annoyed by me with asking so many questions.”
• “I spent quite a bit of time trying to figure out why one side of the spoon produced an 
upside down image while the other side produced a right side up image... I think I figured it 
out!”
• “I truly am interested and am weirdly getting into wanting to be an eye doctor.”

In some regard, then, the experience of the elementary education majors more directly mirrors that of scientific practice, where questions are pursued, at least in part, because they are inherently interesting, questions are taken up with friends and colleagues, and puzzles haunt you long after leaving work at the end of the day. 

More info on my favorite ESTJ

Students are reading "Talking Their Way into Science."  I posted this on my private blog but want to add it here, since we were discussing this idea here recently:

In the book, Karen Gallas describes a student, Donald:

This is a very raucous discussion. I notice that all the children are participating except for Donald, our most knowledgeable science buff. I realize that he never speaks in a Science Talk unless he has had prior information on the topic.  He is unable to engage on this one. I wonder if too much prior knowledge makes you less able to work on open ended questions. In some ways these talks make a level playing field…

Later in April, my notes record this observation during the talk, Does the universe end?

Donald entered this discussion first to clarify the question and then to make an extensive display of knowledge. He spoke in very quick spurts, like he was reading from a book, kind of a staccato delivery of facts… His vocal intonation was very high pitched, authoritative, and impatient…

The pattern that seemed to be emerging that first year, was that Donald would participate only when there was no risk in joining us because he could display his knowledge, and when he did say something the tone of his remarks was always intimidating.

… Perhaps the talks violate their sense of what science is. In other words, they have been prepared before entering school to feel “scientific.” For them, science is like saving money in a bank: Acquire an extraordinary amount of information, and that makes you scientific.

 My ESTJ student recognizes herself in this! - she notes:

I’m Donald in the book! Ha ha!

I don't entirely agree-- she's not intimidating (or not deliberately so - she has a very strong presence but you don't feel threatened by her) - but it's fascinating that she sees herself as the Donald of our class (and I do agree, in part, with that assessment). I'm also excited to hear how it is to read a book saying the Donalds are not doing the "right thing."  And she might be able to say "here's how it feels to be Donald" - someone who enters a class with a strong science identity that has the class structure undermine that.  I really want to get her ideas on this.