tt_icon_170Despite my better judgment, I invite TI staff educator Eric Muller to do one more set of activities on my Teaching Tips podcast —several things you can do with soda straws.  Listen to the episode – The Last Straw.

Holding Charge activity (PDF)
More of Eric Muller’s activities

Hey guess what!  Science Teaching Tips was just highlighted in the Websights section of The Physics Teacher.   Woo hoo!

I’ve got a new episode of  the podcast posted — The drama of the immune system. This is one of the favorites of our group at the Teacher Institute, and teachers are always asking Tory to do this little bit of theater.  In this classroom activity, staff educator Tory Brady shows you how to make the immune system into a bit of drama.  This is especially good for K-8 students, to help them understand the roles that each of the main characters in the immune system (macrophages, white blood cells) play.  Heck, I found it helpful to make all that vocabulary into a little story.  Much more memorable.  Enjoy!

“A Time for Telling” is the title of one of my favorite papers of Dan Schwartz (Professor of Education at Stanford). In it, he argues that lecture isn’t all bad. We complain that lecture (or “direct instruction” in ed-speak) doesn’t result in a lot of learning for our students. This has been shown again and again, in a lot of studies. But it’s pretty hard to completely eradicate lecture from our universities (or high schools, etc.) — it’s a pretty efficient way of communicating information. But if students first struggle with the ideas and concepts, then they’re prepared to learn from it. This is called Preparation for Future Learning.

For example, you could imagine (and it’s been shown) that students who first invent the idea of density (by being given the task of coming up with a way to describe how many clowns there are per square foot at a circus) will be better able to answer a question about the density of water than, say, a student who was just given the formula for density and shown a worked problem using gold. And a recent study by Schwartz shows just that, that those students who first invented the solution were better able to transfer the idea to a new situation. He writes:

Direct instruction is important, because it delivers the explanations and efficient solutions invented by experts. To gain this benefit without undermining transfer, direct instruction can happen after students have engaged the deep structure, per the Invent condition. [The students who invented the solution on their own] performed just as well on a subsequent test of word problems about density and speed. Direct instruction becomes problematic when it shortcuts the appreciation of deep structure. Across conditions, students who encoded the deep structure of the clown problems were twice as likely to transfer. It is just that fewer students in the Tell-and-Practice condition encoded the deep structure, because they had received direct instruction too soon.

Similarly, he later cites a study that found:

For example, college students learn more from lectures and readings when they first work with relevant data compared to when they write a summary of a chapter that explains the same data .

In some instances, he says, it is useful to just receive direct instruction because the goal is to build rote, routine skills. But in math and science, this isn’t the case:

In math and science, instruction cannot exhaust all possible situations. Transfer and adaptation are important. Although automaticity is important for some facts such as “2 x 3 = 6,” real situations rarely come with formulas attached, so students need to learn to recognize the relevant deep structures. Moreover, the cumulative curricula of math and science mean that students should build a base of knowledge on deep structures from which future learning can grow and adapt.

But teaching this way brings up the problem of assessment:

In the current milieu of high-stakes testing, standardized assessments largely measure routine expertise; namely, efficient recapitulation. If educators want students to become adaptive, innovative citizens who keep learning through changing times, current assessments do not fit. A better fit would map students’ trajectory towards adaptive expertise. Ideally, assessments would examine students’ ability to transfer, particularly for new learning. Such assessments would include resources for learning during the test (for example, a simulation that students can freely manipulate).

There’s always a lot to learn when you start teaching.  But this new teacher’s story was particularly striking to me.  When she just started teaching, she was fresh out of the Peace Corps in West Africa, and this left her little prepared to teach chemistry in a portable classroom with, among other things, no proper way to store lab chemicals.  Listen to this new teacher’s story (“Huh?”) in the latest episode of my Science Teaching Tips podcast.

I didn’t come up with that title.  That’s the title of a lab report turned in by a disgruntled physics major after the obligatory upper-division laboratory.  It’s kinda famous in the physics circuit.  Read it.  It’s funny.

Quotable quote:

Check this shit out (Fig. 1). That’s bonafide, 100%-real data, my friends. I took it myself over the course of two weeks. And this was not a leisurely two weeks, either; I busted my ass day and night in order to provide you with nothing but the best data possible. Now, let’s look a bit more closely at this data, remembering that it is absolutely first-rate. Do you see the exponential dependence? I sure don’t. I see a bunch of crap.
Christ, this was such a waste of my time.

I just sent this link to some of my colleagues who are starting to discuss upper-division labs at the university.  What do we want students to get out of them?  What are our goals?  I love the above lab report (have you not read it yet?  Go read it!  It’s short) in part because it seems to sing the truth of what’s broken in a lot of these labs.  We give students shoddy equipment and ask them to go and confirm something that we’ve known to be true for over 100 years.  They write it up.  It’s just as cookbook as when we ask elementary students to measure the temperature of boiling water.  But don’t we expect more from students at this level?  Shouldn’t they be able to apply critical thinking skills and do true inquiry science by the time they’ve undergone hundreds of hours of instruction in physics (or any science)?  Shouldn’t they have a working thermos?

We remember these great teachers who have taught us so much about the world. But did they really? Some educators firmly believe that you can’t teach someone anything — rather, they have to learn it for themselves. A great teacher is someone who helps make that happen. A great teacher is a facilitator of learning more than an explainer. I’ve often wondered about this, since I certainly remember the great explainers from my past. Did they really teach me nothing? Are great explainers like televisions of education — entertaining and interesting but we don’t actually retain what they try to channel into our brains? I do think this might be the case. When I’ve actively struggled with something already, and just can’t put two ideas together in the right way, a great explainer can help me make the connection that I’ve failed to make. But if I haven’t already struggled with that material, then the explanation is cool and beautiful, but quickly slips through my grasp. In EducationLand, this is called Preparation for Future Learning, or PFL. In PFL we make students struggle with an idea so that they’re prepared to listen to a lecture or to learn whatever material we want them to learn.

I just posted a new episode of my Science Teaching Tips podcast in which longtime educator Modesto Tamez shares some thoughts about how he helps students make ideas their own, so that students learn for themselves. It’s called, you guessed it, Nobody’s Ever Taught You Anything.

The Exploratorium has done a lot of fun stuff with the physics of baseball, including a whole website devoted to the science of baseball (where’s the sweet spot on the bat? What are baseballs made of?). One of our senior artists, Dave Barker, has also created the Bat Marimba (photo above). I’ve just posted a new episode of my Science Teaching Tips podcast about the physics of baseball (listen to it here: Hey, batter batter!) with a beautiful performance of the bat marimba. Below is a YouTube video of Dave talking about the physics of baseball and of the amazing Walter Kitundu playing the marimba.

It can be tough to get K-8 students engaged in math, or to really get across the idea of size and scale.  My latest podcast features a talk by math enthusiast David Schwartz talking about some real-world size comparisons that can make size and scale relevant to children’s lives.  Give it a listen!

David Schwartz’s website is at

Title: Science Teaching Tips
Episode: 46.  If you could hop like a frog…


[[AAPT Millikan Lecture: Eric Mazur]]

Eric Mazur (Harvard) was awarded the Millikan prize this year, and this blog post is a detailed account of the marvelous keynote lecture he gave for the occasion. You can download the entire presentation on his website, and I recommend that you do so, because, well, it was marvelous!

The AAPT Press release on the award has this to say:

“Professor Eric Mazur’s Peer Instruction technique has altered the landscape of physics teaching. Numerous teachers have adopted Peer Instruction, enlivening their classes by turning passive students into active learners. AAPT’s Robert A. Millikan Medal recognizes Eric Mazur’s outstanding scholarly contributions to physics education,” says Harvey S. Leff, Chair, AAPT Awards Chair, as well as the 2008 AAPT Past President, and Professor Emeritus of Physics, California State Polytechnic University.

Here’s the content of the lecture.

He opened up with this poem from the “Dear Professor” collection of poems based on emails sent to a real live physics professor and compiled by his wife.

Dear Professor,
I still don’t believe heavy
and light things fall at the same speed.
A feather and a stone, for example.
You kept saying I’d get it
if I lived in a vacuum.
Do you live in a vacuum?

One stark moment in Mazur’s career came when one of his students, taking a concept quiz about force and motion, asked him,

“How should I answer these questions? According to what you taught me? Or according to the way I usually think about these things?”

Why is there this difference, asks Mazur, between the world of physics and the real world? He wanted to know, so he went to Harvard square and undertook to find out. He asked people there who hadn’t taken a physics course whether physics had anything to do with the regular world. Their response?


“Sort of”

“I’m sure in some way it does”

“Yes, definitely. I’m just not sure it applies to what I do everyday.”

So, while there was some hesitation, generally people were pretty positive about the connection between physics and real life. But studies have shown that generally after taking introductory physics, students believe physics is less relevant to the real world than they did when they entered the class! There is something about the way we’re teaching physics that is divorcing it, in students’ minds, from the stuff of everyday experience.


Mazur’s answer is that “spherical cows endanger physics.”

(Don’t know what a spherical cow is? From Wikipedia:

Spherical cow is a metaphor for highly simplified scientific models of reality. The phrase comes from a joke about theoretical physicists:

Milk production at a dairy farm was low so the farmer wrote to the local university, asking help from academia. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the farmer received the write-up, and opened it to read on the first line: “Consider a spherical cow. . .

Mazur argues that — mostly through our textbooks — we paint a picture of physics that is

  • Really weird
  • Different from the real world
  • Truly confusing

Physics is Weird

You’re an introductory physics student. You buy your big fat tome of a physics textbook and crack it open to see what this stuff is all about. What do you see? Really weird pictures, says Mazur. Elephants sitting on tables (with the force of gravity clearly labeled), a tightrope walker walking a rope slung between two capacitor plates, a huge wrench trying to lever the earth (to illustrate torque), a catapult set up to slingshot stones at a sunbather. “I wish I was making this stuff up,” he said, as he showed us one hilarious image after another — monkeys pulling themselves up a pulley, a periscope allowing a penguin to look underwater, a man standing in a box floating in the ocean (Be sure to download the whole presentation if you want more examples — I don’t want to pirate his presentation any more than necessary to make the point).

These textbook pictures are meant to make the content interesting or funny or engaging for students, but they just come across as strange and silly. They certainly don’t suggest that physics has anything to do with the real world. Silly art makes us look weird, he says.

Physics is Different

Image from M. McCloskey, Intuitive Physics, Scientific American 248 (1983), pp. 122-130

Think about the above image for a moment. Which path is right? If you’re a physics teacher or know something about physics, chances are you chose the parabolic path — path C. That’s what all Mazur’s Harvard colleagues chose — he showed us videotape of them.

But what about when he asked the everypeople out on Harvard square? They all chose path B. Why? Things fall straight down. When he asked them what they’d say if he told them that most physicists chose path C, they said

“I’d take their word for it, but I’d want to know why”

“I’d have to see it.”

“I’d be concerned for the world of physics.”

“I wouldn’t believe you.”

“I’m sure you know what you’re talking about, but why would it go so far forward if you weren’t throwing it?”

He then showed us a video of someone running while they drop a ball. And would you believe it? Path B is the closest to what really happens! The runner would have to be running at 25 miles per hour in order to have the ball drop to the ground where his foot falls at the end of his stride. Or, he’s running on some tiny planet where g is 1/100th that on earth. But as physics folk, we choose the path that fits our model, even if the representation of that model is wrong! None of the professional physicists he asked mentioned that the picture was exaggerated — they were even a little offended that he asked them the question! When he asked them what they would say if he said that path B was actually the most correct, they asked him, “In what sense?” The model overrides our personal experience. No wonder people feel physics doesn’t represent the real world. Illustrations like this are really problematic. They look realistic, but the trajectory of the ball is unrealistic. So there is this unrealistic image projected on a realistic background. How confusing! He showed us about 5 pictures just like this one, taken from physics textbooks.

To make matters worse, in an attempt to make pictures interesting and “real world” textbook artists put all sorts of distracting elements in pictures: hikers, baseball players, bridges, trees. He showed us, for instance, one picture of a boy throwing a ball from a bridge, with trees in the background. The parabolic path of the ball was marked on the diagram. He then showed us results from an eye-tracking study of that image, showing what parts of the picture people looked at. Where did they look? The boy, the ball, the trees, the text showing the height of the bridge. Do they look at the parabolic trajectory at all — the whole point of the diagram? Not really.

These realistic renderings of images are a distraction, he argues, not a help. These are unnecessary elements.

Physics is Confusing

In this part of the talk, he pointed out errors in textbooks, including his own. He asked us, first, are the components of a vector (eg., the x and y components) themselves vectors? There was some disagreement in the audience. There appears to be some disagreement in the textbooks too, as he showed us pages within the same textbook that first showed the components to be vectors, and then scalars, and then vectors again. In his own textbook, he found he was using confusing language to talk about whether “momentum was conserved” versus “the total momentum is constant”. He argued that because we know what we mean when we say something, we’re unconscious of the errors. We’ve become blind to what is actually written because we know what we intend to say. To the physicist it all makes sense, but the students are confused.

To Sum it all up:

Mazur summed up his main points thusly:

  • Silly art makes us look weird
  • Misplaced realism makes physics different
  • Lack of precision confuses

We need to be more careful in our representations, he says.

An audience member asked him what he thought the simplest concept in physics was. He thought for a while but finally answered that no concept is simple. “Sometimes I’m surprised at how we manage to learn,” he said. No wonder these things are difficult, we’ve taken thousands of years to develop our discipline.

Another interesting story, for those familiar with peer instruction. This illustrates just how much faculty can be set in their ways. He gave a talk to faculty and gave them a challenging question that he knew would be a struggle. Their responses showed that there was not a consensus on the right answer. He asked them to turn to their neighbor and discuss the answer. Generally in his classes, this results in an in lively discussion which results in most students choosing the correct answer because they are able to understand the answer as argued by a neighbor. With the faculty, fistfights almost broke out, they argued so vehemently. When he asked them to revote, the results were exactly the same — nobody changed their mind!
Thank you Dr. Mazur for such a wonderful talk!

I’ve just posted a new episode of my Science Teaching Tips podcast — Which is Closest?

Which is farthest away from the earth, the stars or Pluto? The answer may be obvious to you, but a lot of people get this wrong.  Here’s the task — arrange these in the order from closest to furthest from the earth:  moon, sun, Pluto, stars, and clouds.  Think about it first, and then listen… listen carefully!  It can be easy to miss the mistakes that people make.

We went out and harassed the employees at the Exploratorium with this little survey.  I was astounded by what we found.  Many teachers are.  Linda explains why people (even highly educated people!) answer as they do, and what this means for teaching about science.