Science teaching tools that work

When learning physics, you pick up math skills. But there's a problem when students only learn how to choose equations and plug in the right numbers. The “plug and chug” questions you see on physics tests are of the easier variety. The hard questions are qualitative and conceptual. 

Here is an example of a basic conceptual physics question I saw from NPR.

Two balls are dropped from a building at the same time. Ball A and Ball B are the same size, but Ball A is twice as heavy as Ball B. Which ball hits the ground first?

a) Ball B hits the ground first.
b) Ball A hits the ground first.
c) They hit the ground at the same time.

If you understand Newton's second law (F=ma), you know that both balls hit the ground at the same time.

(Or if you like to guess, you know that c) is always the correct answer)

Even though one ball is heavier than the other, they have the same acceleration, 9.8 m/s/s, so they take the same amount of time to hit the ground.

Even students who have taken physics frequently get this question wrong. NPR reports that lectures are part of the reason students fail to learn the material. Students learn best when they are actively working, not when they passively listen to lectures.

Students do most of the talking in the “Peer Instruction” teaching model developed by Eric Mazur, a physics professor at Harvard. In this model students work together to solve problems in small groups. The professor poses conceptual questions to the students, who respond with answers via mobile devices. If a large percentage of the class answers incorrectly, the students work through the problem in their groups. After discussing with their peers, they answer the question again. The professor exists as a coach guiding the students during practice, rather than as a “sage on stage”.

According to Mazur, the approach works: "What we found over now close to 20 years of using this approach is that the learning gains at the end of the semester nearly triple."

As a physics major, I wish I had taken classes like this when I was in college. Learning through your peers is the best way to learn, especially in science. It also reminds me of an opinion article about science education I read in the LA Times. It referenced a study that sought to explain why some students were more prone to fail first-year calculus at UC Berkeley. The study found that students that never worked with other classmates were the ones that failed, even if they put in the study hours and the effort. The successful students were the ones that studied both by themselves AND in groups, where they helped each other out and figured out exactly where they stood in the class.

One caveat about Peer Instruction: it works best when students come to class prepared (i.e. they have already read through the material). Not all students are going to come to class prepared because many are used to relying on the lectures. As always, the students that go the extra mile and invest their own efforts into learning will get the most out of it.

Also, in this model students answer the same question twice. If only 29% of students answer a question correctly the first time, it sometimes improves to 62% of students who answer correctly the second time. But of course, if you think you answered incorrectly the first time, you can eliminate that answer choice the second time. Odds are that the scores will improve by simply repeating. And I wonder if the students get to see how the class answered overall.

Just some thoughts on group learning.

Dark energy highlights continued

Here is a great dark energy FAQ from Sean Carroll, a physicist at CalTech.

Einstein's greatest blunder (?)

In 1917 Einstein added a fudge factor, the cosmological constant, to the equations in his theory of general relativity. Before adding the constant, his equations showed the attractive force of gravity would cause the universe to implode in a Big Crunch. The constant kept Einstein's picture of the universe static – neither expanding nor contracting.

When Edwin Hubble discovered that the universe was expanding (the rate of expansion is what won this year's Nobel Prize), Einstein threw out the cosmological constant, declaring it his greatest blunder.

But the cosmological constant may still work. In fact, without the constant, the age of the universe is calculated to be much younger than the oldest observed stars. Since this makes no sense, the constant may hold validity.

How do spacetime and quantum field theory ultimately fit together? That has been the big looming question. One proposed “quantum correction” to classical mechanics is quantum mechanical vacuum energy. If there is such a vacuum energy, it may be associated with the cosmological constant.

But there is still an incredibly gaping margin of error: when physicists calculated the vacuum energy they came up with an answer 120 orders of magnitude (10^120 times) greater than what we actually observe. It would take me 2 minutes just to write out all those zeroes.

(hey you physics people, want to delve further?)

With all the advances in modern physics and the accomplishments highlighted by this year's Nobel Prize, there still remains an entire universe (or perhaps multiverses?) of mysteries.

Into the Future...

For the time being, budget cuts caused NASA to scrap its projects investigating dark energy using the James Webb Telescope. Fortunately, in 2019 the European Space Agency plans to step in with its Euclid mission.

The Large Synoptic Survey Telescope (LSST) in Chile will become another source of data for dark energy research.

Dark energy gets attention from Nobel Prize in Physics

*picture from NASA

Three American-born physicists won the Nobel Prize in Physics on Tuesday. Thirteen years ago they first made the startling announcement that the universe is expanding at an accelerating rate. They made the discovery by measuring the brightness of type 1a supernovae, explosions of small stars known as white dwarfs that can outshine an entire galaxy and can radiate as much energy as our sun will in its entire lifetime. The measurements showed that the supernovae were dimmer than what was expected, suggesting that galaxies were moving apart at an increasing rate.

At the time scientists were skeptical of the results – the prevailing view was that the universe was slowing down in its expansion. Yet two teams in competition with each other (one led by Saul Perlmutter of the Lawrence Berkeley National Laboratory, and the other headed by Brian Schmidt of the Australian National University in Canberra and Adam Reiss of the Space Telescope Science Institute and Johns Hopkins University) used independent lines of evidence to reach the same results.

The Nobel Prize brings attention to the study of a mysterious component of the universe called dark energy.


What is dark energy?

The simple answer: we don't really know, but physicists believe that dark energy is the “thing” that causes the universe to accelerate in its expansion. It's a little unbelievable that dark energy makes up about 73% of the universe, and yet we know so little about it. There are three properties to note. First, look at the name: dark. It is 'dark' because we don't see it; we do not observe dark energy interacting with matter at all. Second, it is smoothly distributed. The density of dark energy is uniform throughout space. And third, it is persistent. Unlike particles of matter, dark energy doesn't cluster together or dilute away.

The difference between dark energy and dark matter

Dark energy is not the same thing as dark matter. Again, look at the name. Dark energy is energy – it doesn't consist of particles. Dark matter consists of particles of matter. Physicists think it's there but they have yet to directly detect the particles.  However, they have observed gravitational influences (in settings like galaxies, clusters, large-scale structure, and microwave background radiation) that they attribute to clusters of dark matter.

Dark matter makes up about 23% of the universe. Actual matter – the stuff that the Earth is made up of, and the stuff that you and me interact with on a day-to-day basis – makes up less than 5% of the universe. Crazy.

More to come soon...

Depressing study shows people are depressed

Do studies predict the worst? In Nature’s Trend Watch last week the prevalence of obesity in the US and the UK is projected to grow from 32% in 2007-08 to 50% in 2030 for men, and from 35% to 45% for women. One obese person out of three people seems high enough as it is. But one out of two people is just…depressing.

Another study in Nature reports that mental disorders affect over one third of all Europeans. Can they do a follow-up study of how many of those Europeans got anxious or depressed from reading all the other depressing studies out there?

I generally read study results as interesting opinions that could potentially become facts…or not. Just something to think about. But it is irritating when magazines take those studies and tell you to make changes with your life. “Study says chocolate goes straight to your hips. Try eating vegan tofu desserts instead!” And then “Study says chocolate has antioxidants. Go to See’s Candies today!”

I’ll go be happy now and distract myself on Youtube.

Building a toolbox for science and math literacy

I'm very excited: an opinion article I wrote about why we need more exposure early on for science and math education is published in the San Diego Union-Tribune today! The basics:

1) Science and math can be awesome!

2) Learning math is like investing in a good toolbox to build a house.

3) Having a mentor/having a challenge is invaluable.

You can read more about good toolboxes that help our less-than-stellar education system in science and math here:

http://www.signonsandiego.com/news/2011/aug/20/building-a-toolbox-for-science-and-math-literacy/

Palm trees threatened by invasive pest

What do you think of when you picture southern California? The breezy beach, a cloudless, sunny sky…and maybe some palm trees? Okay, how about a lot of palm trees. They are everywhere. 

Let’s hope our palm trees stick around. 

(photo credit: John Kabashima, UC Cooperative Extension)

The red palm weevil, a small beetle-like pest that can quickly kill palm trees, was first discovered in California last year. Weevil larvae burrow deep into the trunks of palms and grind its insides into mush. Adult weevils munch on palms, including the top-most leaves.

You can read more about it in an article I wrote for this month’s issue of CAPCA’s Adviser magazine, “What’s Bugging California’s Palm Trees?” I had the opportunity to interview Mark Hoddle, an entomologist at UC Riverside who researches the red palm weevil and conducts field work to contain the pest. He keeps a well-documented, up-to-date blog here. 

Speculated to have come from Southeast Asia, its invasion now threatens palms in urban areas, native palms in the desert, and California’s date crops and palm nurseries. In May this year, a second weevil species was caught in a trap in San Diego County. Traps are currently set up around the first sighting in Laguna Beach and along the Mexico-CA border (where the second species was found). 

Ever since doing this article I have put on my palm tree glasses. As a southern California native, I am so used to palm trees that they blend into the background. They weren’t so different from any other tree. But knowing that they are iconic to our state, especially for those who come to visit, I can see ‘em now! 

Pale Blue Dot Animations

There is a whole world to explore within a pinhead. Consider that an atom is roughly seven orders of magnitude smaller than a pinhead, something you can still see with the naked eye. If you blew up that pinhead to the size of the earth, you could at last hold an atom in your hand like you would, say, a water balloon.

And then there is Carl Sagan shrinking the massive size of the earth to a pale blue dot.

This "joyful, sad, sweet, and wonderful" animation posted on PBS Nova's blog got me thinking. It captures an excerpt from Carl Sagan's book A Pale Blue Dot.


Pale Blue Dot - Animation from Ehdubya on Vimeo.

Science is a tool that can help us better appreciate the beauty of nature. It doesn't reduce the mystery and art of life by explaining/revealing its underlying mechanisms; rather the opposite, it gives us more perspective.

Taking a walk outside helps me see I'm a tiny creature amidst people, cars, buildings, trees, mountains... I'm still trying to imagine zooming out on me, my city, California, the US, and then the earth until there is nothing but a pale blue dot...