Tag: physics

Circadian rhythms and a nature deficit

Nature trail in winter.

I remain fascinated by the Brazilian study that found that kids living in homes without electricity did not have the same sleep deprivation issues as those with electricity. I thought of it again recently when I ran across the term “nature-deficit disorder” in Oak Hill Montessori school’s newsletter.

Unstructured nature time is so important because children live through their senses. When they are right there in the forest, they are getting a primary multi-sensory experience of nature as opposed to the secondary, often distorted, dual-sensory view presented by TV. – Daniels, 2009 (p. 4)

The idea of nature-deficit disorder comes from the book “Last Child in the Woods” by Richard Louv. Written in 2005 and updated in 2008 with a bunch of practical things you can do to change things, Louv’s book advocates for more time in nature because, “a growing body of research links our mental, physical, and spiritual health directly to our association with nature.” Not only does it affect our individual health, but directly experiencing nature also helps increase environmental awareness (which ties into the Montessori peace curriculum). Louv argues that children have a fundamental right to walk in the woods:

Science sheds light on the measurable consequences of introducing children to nature; studies pointing to health and cognition benefits are immediate and concrete. We also need to articulate the underlying “first principle”—one that emerges not only from what science can prove, but also from what it cannot fully reveal; one that resists codification because it is so elemental: a meaningful connection to the natural world is fundamental to our survival and spirit, as individuals and as a species. Louv (2009)

I can’t say I disagree very much with this diagnosis. My adolescents are too often opting for technology rather than being outside, especially if it’s in nature. This is one reason my students are building the nature trail. The trail has been coming along slowly though, but the seasons are changing and we’ll spend more time outside in the warmer weather. The timing is also nice because we’ve just finished covering simple machines in physics. There are logs and junk to be moved and saplings to be cleared.

Note: Louv has a long list of links to print and broadcast articles on the whole “nature-deficit disorder” concept.

Saturn’s aurora borealis

Credit: NASA via Wikimedia Commons

I came across this beautiful animation of the auroras on Saturn. The auroras are caused by charged particles (ions) from the sun, the solar wind of protons and electrons, are focused down onto areas near the poles of a planet by the magnetic lines of a planet’s magnetic field. The ions hit the atmosphere colliding with atmospheric gas molecules like nitrogen and oxygen causing them to become excited and spit out electrons (becoming ions themselves). Molecules are not “happy” when they’re missing electrons so they’ll capture one to become “fulfilled” (fill their outer electron shells). It’s when they recapture electrons that they give off the light that we see as the auroras.

On Earth the auroras are green or brownish-red (from the Oxygen) and blue or red (from the Nitrogen). Saturn’s atmosphere is mostly hydrogen and helium so we’re not quite sure what color its auroras are. The auroras in the animation were colored in by NASA since the camera on the Cassini spacecraft is black and white.

The video clip below gives a nice explanation of auroras.

How much technology in the classroom?

The title of Mark Bauerlein‘s book is somewhat provocative. It’s called, “The Dumbest Generation, How the Digital Age Stupefies Young Americans and Jeopardizes Our Future.” As I am very much an advocate for incorporating technology in the classroom, it’s not too unexpected that I disagree with large parts of his thesis.

Yes there is probably an important link between the brain and the hand that facilitates creative work. But it does not necessarily follow that, “Writing by hand, students will give more thought to the craft of composition. They will pause over a verb, review a transition, check sentence lengths …” (Bauerlein, 2010). As we work on habits of revision there seems to be no real reason why they should spend more time on improving a sentence they’ve hand written than one they’ve typed. True, if students are conditioned to write in short rapid bursts of texting it will translate into their other writing, but it is the role of the teacher to help them delineate these different genres of writing. I also have not seen the evidence that writing by hand is any less abstract than writing by typing on a keyboard. We are already expressing ideas using an abstract medium, words, why is one form of expression better than the other?

Where I do agree with Bauerlein is on the need to take breaks, even substantial ones, from technology and the online world. Where I see the greatest need for this is in aiding student’s comprehension of the natural world. You live too long in the virtual world and you begin to translate that experience into the real world. Yet the virtual world remains a model of the real one. It is simplified and enhanced to make it a more enjoyable experience, so the lessons you learn there do not truly apply to the real world. In addition, physical experience in the virtual world, at least for now, cannot create the kinesthetic, mind-body understanding of the laws of physics and biology that you learn from real-world games and just walking along the nature trail. This is why I am a firm believer in our week-long immersions every six weeks.

So I continue to allow my students to introduce new technology to the classroom, as long as they can show me that it is effective in helping them learn. The latest thing is the proliferation of iPod Touches. I like the iPods because of apps like iSeismo that lets you monitor vibrations in 3D. However, on our recent visit to the Le Bonheur Hospital a number of my students took their notes on their iPods. I personally don’t believe that these are more effective than pencil and paper because you can’t combine text and images very effectively on an iPod, but they did take copious notes (which they were quite proud to show me). I’m planning on giving them a quick quiz to see what they learned from the trip so we’ll see just how effective their note taking was.

We’re all swimming in a sea of new technologies, and we can’t really tell what will benefit and what will hinder without trying them out. So, I at least conclude that the key goal of middle school education should be to create in students a core competence and confidence that will help students navigate steadily in this world of much information and rapidly changing fads. A fundamental understanding of the mechanisms that underlie people’s behavior is key. Know yourself and understand how societies behave. The first is not trivial and the second requires drawing general conclusions from a lot of historical data, which is quite challenging for most adolescents, but that’s why we teach the way we do.

Note: There is an interesting discussion of the use of technology in the traditional classroom going on now on Will Richardson blog post “The Big Questions: Now What?“

Waves and earthquakes

There are a lot of Earth Science applications that deal with waves. Seismic waves from earthquakes are a major one that is particularly pertinent after the recent Haitian earthquake. There are quite a number of lesson plans dealing with seismic waves at Larry Braile’s website. Most of the lessons are as practical demonstrations pdf’s and some use downloadable software (Windows only unfortunately), but there are some online applications as well.

In terms of online resources, the IRIS network, produces nice maps of recent earthquake locations. It also has a good page with “Teachable Moments” regarding recent earthquakes. These include the above video of why the Haitian earthquake did not produce a tsunami.

Although it’s not directly related to waves, I particularly like the thermal convection experiment on Braile’s website. It provides, with a baking dish, a sterno can, some water and some thyme, a great example of the convection in the Earth’s mantle that drive plate tectonics.

iSeismo app

Those who know me know how much I like the iSeismo app for the iPhone. The phone as a built-in accelerometer and the iSeismo app uses it to show the movement of the phone in three dimensions. The app show three graphs (seismographs), the first two show horizontal motions and the third vertical motion. So, if you put the phone on the table and hit the table the third line should jump up and down.

You can also export the data from the phone (or iPod Touch), and since the phones’ times should be synchronized pretty well, there should be a way to use two phones to triangulate the location of an impact, say on the floor in a room, in the same way that seismologists use seismographs to locate earthquakes. That would make a great demo if it was easy enough to do.

Update: iSeismo can also be used as a heartbeat monitor.

Quantum mechanics – things you should know

Diffraction of light through a grating. Image from http://commons.wikimedia.org/wiki/File:PatronRefraccionCD.jpg

The way sub-atomic particles behave is weird. They don’t fit very well into our everyday experience of the world, but the math and the experimental observations hold up. Chad Orzel has an interesting post on the seven things everyone should know about quantum physics that’s written in language a lay person can understand. This does not make the concepts much easier to grasp intuitively, because, as I mentioned before, quantum mechanics is weird, but it does explain things so we can begin to grasp the big picture of how the universe works. It also helps explain why they’re building the Large Haldron Collider. So though you may not know the answers, you’ll at least have an idea about what it’s about when your students ask.

Waves and interference

There are lots of interesting interactive wave demonstrations on the web. The particularly interesting ones are the ones that show interference. Some of them make your eyes water. Others make your ears hurt. These simple animations show superposition (constructive and destructive interference) very nicely, but the language is a little advanced.

What I like about Dan Russell’s 2d animations is that they show the wave motion using particles. If you track a single particle with your eye you can see that while the wave moves from one side of the area to the other, the particles just move back and forth in the same general region.

Longitudinal wave
Longitudinal wave (from Russell, 2001).

I like this demo because you easily control the wave amplitude and lengths of two waves and it shows how they superimpose.

This animation of wave interference is nice because when you click on the 2d animation it shows the two waves’ effects at the point you’ve chosen as curves. You can choose points to show both constructive and destructive interference.

Constructive interference (screen capture from animation by Ng (Retrieved 2010)).

Destructive Interference (screen capture from animation by Ng (Retrieved 2010)).

This elegant but somewhat complex video shows the two dimensional sine waves generated by a rotating wheel.

Sine waves from a rotating wheel (from animation at Russell Kightley Media)