Me, I’m madly packing to go canyoneering in Utah for Thanksgiving.  But I wanted to leave any erstwhile educators still trying to keep their kids’ attention over the holidays with this link to Thanksgiving science resources from the NSDL.

Happy turkey day!

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Just got this from Bob Park’s What’s New column. Looks like Gingko has failed a double-blind study to see if it really improves memory. I’ve been taking it for a while, in hopes that it would defuzz my neuronal connections (I’m not that old, but my memory took a real hit ever since I was on crazy antimalarial drugs in Peace Corps 10 years ago).

This reminds me of when a friend told me that there’s no reason why Airborne would improve your immune system. I was really angry at him for telling me this. Airborne definitely seems to keep my colds from getting too severe. If that’s due to a placebo effect, then hearing scientific reasoning that it shouldn’t work will destroy my placebo effect. Especially since my belief structures are particularly sensitive to scientific evidence.

Here is what Bob Parks wrote. I’m a bit perturbed by what he writes at the end, that all these other remedies have failed double-blind tests. It sounds to me as if he expected this to happen, because herbal remedies are by their very nature “unscientific” or something. I don’t see why some of these “natural” remedies couldn’t have something to them. After all, we take Zinc to help our immune system. That’s just a mineral. What makes a mineral less “woo woo” than a plant (like Echinacea)?

3. GINKGO BILOBA: A TIP ON WHERE YOU CAN CUT EXPENSES.
Annual sales of the herbal remedy Ginkgo biloba in the US are at $249
million. It is alleged to prevent memory loss. It doesn’t. In its
first large trial, half of 3,069 volunteers 75 and older were given of
Ginkgo biloba daily, while the other half were given a placebo. They were
assessed for signs of dementia every six months for 6 years. Neither the
patients nor the doctors doing the assessment knew which group patients
were in. The group getting the placebo actually did slightly better,
although the difference was not statistically significant. France is
planning an even larger study. Ginkgo has a lot of company. One after
another, the most popular herbal supplements, ephedra, Echinacea, St.
John’s Wort, have failed in double-blind, placebo controlled studies.

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This is from the Exploratorium — several opportunities to connect your classrooms with polar science, including via live webcast three times a week!

Ice Stories: Dispatches from Polar Scientists
Webcasts at 1:00 p.m. PST
December 7, 2008–January 4, 2009
Tuesdays, Thursdays, Fridays, and Sundays
Connect Live with Antarctica!
E-mail polar@exploratorium.edu or call (415) 561-0359
You’re invited to chat live with an Antarctic scientist during one of
our Webcasts! Contact us to arrange a connection online or by phone.
Or be part of our Webcast studio audience at the Exploratorium.

Watch Webcasts
http://explo.tv/icestories
In celebration of the International Polar Year, we begin a new Ice
Stories Webcast season from Antarctica on December 7. Visit explo.tv
for a schedule of upcoming shows and to watch archived Webcasts on
demand.

Follow Dispatches
http://icestories.exploratorium.edu/dispatches
We gave polar scientists cameras and blogging tools and asked them to
document their fieldwork. Follow along on their adventures and see
what it’s like to be a research scientist in an extreme environment.
Questions and comments for the scientists are invited!

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I just posted a new episode of my Science Teaching Tips podcast on Mini Labs. Give it a listen!  “Zeke” Kossover is a teacher in the bay area, and he’s always posting wonderful tips about teaching — from great organizational tips to the best places to find cheap electronic components to astute tips for teaching physics.  In this podcast I got him to talk about an idea he’s used in his classroom and taught to many other science teachers — Mini Labs.  The idea is to take a science concept and write a very focussed, brief lab activity around it.  He has some concrete tips for making these labs successful and why they can be a useful addition to your class, without taking the amount of time and equipment that full lab experiences can require.

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A free workshop for educators on December 9th from the National Science Digital Library:

This Web Seminar will focus on dynamic online resources you can use to teach your students about the chemistry of water through the NSDL Chemical Education Digital Library. Join presenters Dr. John Moore, W. T. Lippincott Professor and director of the Institute for Chemical Education, and Dr. Lynn Diener, Assistant Professor, Mount Mary College in Milawaukee, Wisconsin and guests Jon Holmes, Editor of Journal of Chemical Education Online and Dr. James Skinner, Chemistry Professor at the University of Wisconsin-Madison for this seminar for educators of grades 9-12.

Register for this free seminar

Learn more about NSDL NSTA Web Seminars

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I just had a short article published in The Physics Teacher (in Websights) on useful blogs for physics teachers.  (Woo hoo!)  That article was somewhat truncated from the original, so for any of you who have found my blog through that article, here is the full article as I wrote it.

PDF-of-physics-blogs (with lots of juicy links to blogs)

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Hey hey, I’ve got a twofer in the current issue of the Physics Teacher!  One is my article on the chemistry behind the saltwater battery. The other is an article on blogs that physics teachers can use.  I’ll post the full blog article (the published one was cut quite heavily) a little later!

Here’s the crux of the saltwater activity:  When you connect cups filled with salty water together, you can make a current strong enough to ring a buzzer or light an LED.  Neat!  This article explains the electrochemistry behind this popular activity so that physics teachers can know enough chemistry to understand a lot of the weird behavior that they see.  I’m a physicist, so I don’t know much chemistry.  So this paper is kind of neat in that it’s a joint venture between myself and my dad, retired physical chemist Dennis Chasteen.  My mentor Paul Doherty is also a co-author.

The construction of the cell is largely borrowed from the Exploratorium’s Square Wheels book (thanks to master tinkerer Don Rathjen!)

You can download a PDF of the article here.

Here are some supporting materials on my mentor and coauthor (Paul Doherty’s) website.

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This is the last in a series of three posts on Dan Schwartz’s work on preparation for future learning, or helping students learn skills instead of rote facts so that they can apply their knowledge to new situations. All pictures in this post are courtesy of Dan Schwartz.

Contrasting cases

In the previous post, I showed Dan’s use of contrasting cases in helping students understand density and ratios. Why is it important to show students different cases, instead of the best single example of something? Well, he said, think about perception. Consider this circle:

We immediately recognize it as a circle. It is, after all, not a square.

But, in fact, it is many things. It’s a empty circle. It’s a circle created with a black line. It’s a largish circle. Here are a bunch of contrasts to this circle:

We’re abstracting “circle-ness” from the single example, but that’s because we recognize circle-ness already. These contrasting cases would be important if we were first learning about circles.

Here are some contrasting cases of something familiar to us:

After all, what is the best way to teach Japanese speakers to say the sound “L,” which doesn’t exist in their language? Give them the purest example of an “L” sound that you can find? No, it’s to let them hear “R” and “M” and all the other sounds, so they know what the “L” is NOT in addition to what it IS.

But, this is what we do in instruction! We give students the purest example of something that we can. Consider, for example, this picture.

This is a perfect example of this breed. Now, tell me which one of the following is the same breed?

An expert will look at the width of the ears, the curve of the nose. But a novice can’t look at these pictures and see the immediate resemblance to the example picture. (I forget which one was the correct answer, but I think it’s the last one. The hair length is an extraneous feature, the ear shape is most important.)

It would have helped if, first, an expert had used the following picture with contrasting cases to help you learn about ear shape (what does “rounded” ear shape look like? How wide is “wide”?). You need to be oriented to understand the key structures in what you’re seeing. You can’t just look at the picture below and learn from it, though — a bunch of different examples are confusing to a novice. The expert’s role is to help them make sense of the different cases.

An example activity

Here, for example, is his activity where he asks students to invent a reliability index for a pitching machine. He gives them several different cases so they have to find a general solution which fits all these cases. This, after all, is what we do in science – to find a general solution that fits many cases.

In my previous post, I gave his activity for teaching density using clowns in buses.

The way he uses these in the classroom is to have students explain their classmates’ solutions to each other. That means that each student’s solution has to be written clearly enough so that someone else can understand it. This act of public “publishing” of the results gives students a bit more motivation to come up with a good solution. On the other hand, the goal of this task is NOT to come up with the “right” solution! It’s to prepare students to understand the expert solution (in this case, the idea of variance) when it’s presented.

Expert blind spot

As experts in a subject, we know an amazing amount. What we’ve learned has been compressed into a bunch of huge steps. We don’t recognize the huge number of things that we’re doing when we do what seems to us to be a single step (such as computing a ratio). We need to decompile our knowledge for the novices. In order to do this, it’s good to have an intelligent novice around — someone to ask us a bunch of questions at every step so that we can see what it is that we are doing in any task. Once you’ve discovered some key, fundamental idea that is needed to solve the problem, that’s a great place to put an invention activity. Examples are density, vectors, variance, and other fundamentals.

What these activities are not:

• Not just brainstorming
• Not puzzlers
• Requiring a flash of insight to solve
• Not pure “discovery” tasks
• Not to replace standard instruction

What these activities ARE:

• Students make answers for one case, and recognize it doesn’t generalize to the others
• Learning is incremental
• Students don’t have to find the right solution to benefit from them
• Students should start to notice the variables that matter
• Students are told to invent a form of representation
• They are visual
• These activities are used strategically to communicate fundamental key ideas (like density). Not used for everything.
• Prepares student for standard instruction

To make these cases yourself:

• Think about your own knowledge to isolate key concepts
• Think of each case as an experimental treatment to isolate a key variable
• Or, think of formulas or units and make sure they contrast for each case
• Have some sense of likely misconceptions so you can create cases that will highlight probable “traps” students might fall into
• Make them approachable. You don’t have to be as frivolous as the clowns example, but it should be done in a context that’s different from what you want students to learn (like physics). Then you can help students map it into the new context.

What about assessment?

Dan’s main point is that our assessments need to change in order to use this kind of instruction. If we value students’ showing that their learning is adaptive, we have to give them a chance to demonstrate this on a test, to demonstrate an expert level of perception.

What do I mean by expert level of perception?

What do the images below say to you?

The novice answer (“car,” “bird”) is not very precise.

The expert answer (“2007 BMW X5″ or “indigo bunting”) is much more precise, and relies on deep recognition of various features. We should test students on this more broad ability to apply their knowledge. For instance, geology students should be able to extract some important features from this picture of a landslide:

This doesn’t have to be a perceptual test — in the previous post, the “green people” vs. “blue people” example relied on students ability to recognize the variability in a data set.

I think this stuff is incredibly powerful. Let me know of any more activities that you come up with or you know about!

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Here’s a great video of what happens when you pop a water balloon in space.

This is a nice clear lesson about surface tension and the war between different forces. When you take away gravity, then surface tension is able to hold together a much larger blob of water. It no longer has gravity trying to pull the water blob apart and then air drag breaking it up into droplets.

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In my last post, I wrote at length about Dan Schwartz’s work about teaching students how to learn by having them create a solution to a problem before you give them the standard lecture about how to solve that kind of problem. I wanted to give you an example of this kind of “Preparation for Future Learning” activity, in addition to the batting machine example in the previous post. All images are courtesy of Dan Schwartz at AAA Lab.

This one is to help students learn about density. The task is below.

And here are the graphics for the task.

The key to notice here (and in the previous batting example, though I only showed you one example of the batting machines) is that he uses contrasting cases to teach this concept. There are different buses with different amounts of clowns. These cases are chosen carefully so that the student must come up with a solution that satisfies all these different cases. For example, the number of clowns in the bus does not distinguish between the very first and very last cases shown on this sheet (for which the answer would be “2″ for both cases, which are clearly different).

He found that those students who first invented this density ratio were better able to then use this knowledge to understand spring constants (another ratio) than those were were just told the formulas for density. That data is shown below.

More on how to write your own preparation for future learning activities in the next post….

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