Discovery Channel has a nice video on using a large tower, set at the center of a large greenhouse in the dessert, to generate thermal convection to power electrical turbines.
Solar convection towers
Category: Natural World
Solar cells
How do solar cells (photovoltaic cells) work? There are very simple explanations, but you can probably find a video with any level of complexity you might want.
This video from the U.S. Department of Energy is fairly general and makes a nice introduction:
This video adds some useful detail.
For even more detail, NASA’s page on photovoltaics is very good, and Scientific American has a neat little interview with Paul Alivisatos that goes into the parallel between photovoltaic technology and photosynthesis.
Simple animations about different energy sources
The UK Science Museum has a set of very simple videos describing how different sources of energy are created and harnessed. They are very simplified but perhaps useful introductions to how things like solar cells work; how oil and natural gas form; what is fusion and how it might be harnessed; how tidal power works etc.
8% of human genes come from viruses
Apparently, 8% of human genes have been spliced in by viruses.
The assimilation of viral sequences into the host genome is a process referred to as endogenization. This occurs when viral DNA integrates into a chromosome of reproductive cells and is subsequently passed from parent to offspring. – University of Texas at Arlington (2010)
Seasons wheel
A beautiful intersection of art, science and abstract thinking. An assemblage of photos compressed into a circular graph by Fernanda Viégas and Martin Wattenberg.
Pickwick Landing Hydroelectric Dam
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The hydroelectric dam at Pickwick Landing on the Tennessee River is an almost ideal place to observe electricity generation and transmission. It was a serendipitous discovery though. After our failure to arrange a tour of a dam in Arkansas on the last immersion, we did not even try with this one.
The dam is right next to Pickwick Landing State Park where we camp when visiting the Shiloh National Battlefield. We’d arrived early at the park on the day before our visit to Shiloh, and having seen the dam and its locks on Google Maps’ satellite image (click the satellite button on the map above), I thought it might be useful if we drove over.
Coming around the northern side of the dam we spotted, right next to a parking lot, an old turbine from the dam that had been set up for display. It is amazing how big these things are, but what was really neat is the fact that if you listened, you could hear the whine of the modern turbines coming from the generators deep inside the dam.
Standing over the old turbine was an enormous high-voltage wire tower, sparse metal frame and truncated arms like a benevolent grandparent leaning over a plump, but scared child. The line of towers are connected to the generation station in the dam by power substation just across the street from the old turbine. The substation’s large transformer drums were obvious even from across the road.
Crossing southward over the dam, there is a road that runs westward along the edge of the river that allows a good view of the downriver side of the locks. We were lucky enough to see a barge passing through, although with the traffic on the river the locks are probably always busy.
When we got back to the park the students draw a diagrams of the dam. They don’t do nearly enough diagrams given the importance of drawing in connecting the body and the mind (something I plan on rectifying in the next cycle) so this was a good experience for them. It was also a reminder to always keep their writer’s notebooks with them because then they could have drawn their diagram while they were at the dam looking at the thing.
Greenhouse in a bottle
The BBC has an excellent video demonstration by Maggie Aderin-Pocock of how to demonstrate how additional carbon dioxide in the air results in global warming. She uses baking soda and vinegar to create the CO2 and lamps for light (putting the bottles in the sun would work just as well). You’d also probably want to use regular thermometers in the bottles if you don’t have ones that connect to your computer.
Fossils at Pickwick Landing
Along the edge of Pickwick Lake are outcrops of sedimentary rock being slowly broken apart by the action of the waves on the reservoir. We stopped for lunch at Shelter #6 in Pickwick Landing State Park (see map) before finding our cabins for this immersion. Located at the eastern edge of a triangular ridge of land girded by drowned river valleys on two sides the shelter is almost surrounded by water. On a beautiful, clear day at the beginning of spring, with temperatures verging on t-shirt weather, tiny flowers blooming in the grass and tree leaves just sprouting, it was an almost perfect time and place to take a break after a long drive.
Yet despite the fact that we were eating later that we normally do, half the class walked right past the shelter and down the rough slope to the lake’s edge. There they found fossils. Beautiful crinoids were weathering out of thin (4cm thick) alternating layers of sandstone and limestone, their long fossilized necks resisting while the limestone around them slowly dissolved away. They also found bivalves partially exposed on the face of the broken cliff and in the small pile of tallus. There were even a few thin sandstone wedges sitting on the rocks at the edge of the water that looked like fossilized burrow molds. It was quite fascinating.
Neither the word “science” nor the phrase “natural world” was used, and they brought the questions to me, which I always consider better than me asking them. Next year when we study Earth History perhaps the subject will be considered boring when we see it in the classroom, but today, out there on the rocks at the edge of the water, they got a great primer.
This stop, planed solely as a lunch break was so successful that I now wonder if I should plan the immersion trips to introduce the topics we cover in class rather than using them to integrate what we’ve already seen. Let the outdoor experience be the “spark the imagination” part of the lesson. I’m not sure, but it’s something to think about.
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