physics – Page 17 – Montessori Muddle

Lego Mindstorms

I’ve been curious about the Lego Mindstorms robotic systems for a while now, and I had my first chance to try them at the St. Louis Science Center.

The kits come with a micro-controller, a few motors and some sensors. While there are quite a number of ways of assembling these to make robots, the ones at the science center were pre-built except that you could just plug in a bulldozer or sweeper attachment (and a head which was purely decorative). This limited the degrees of freedom to three, which made it easier to program something useful in the hour we had with the robots.

The programming is very basic. There are two sets of instructions, one to control the movement of the robot in general, and one to control its response when the sensor detected a change in the environment. The objective of the science center’s game was to clear off a set of objects from a white rectangle within five minutes.

You could tell the robot to move forward, back or rotate while it’s on the board and to activate its sweeper or shovel. So a full program could have just five elements; general: lower shovel –> move forward –> rotate; sensor: move backward –> rotate. With these strict limitations, the programming interface is also very simple; you plug in blocks with each instruction in the series for either the general movement or the sensor reaction. With all this simplification, I’m not sure just how much the students learned about programming from our short session.

The full kit from Lego offers more freedom to design robots and thus more flexibility with the programming interface so with a little thought it could be easily integrated into the curriculum. At about $300 each the system is a bit pricy, we’d probably need to get one kit for each small group of 3-4 kids. They would probably be worth it however if we used them more than just once.

I’ve been playing with the Basic Stamp micro-controller for a while, and while it offers almost infinite flexibility, making it more useful for practical applications, it does not provide the immediate gratification of the robots, and the ease of assembly to make it the better tool for introducing robotics to middle schoolers. I still, however, tend to favor practical applications, so perhaps I can persuade a student to do an advanced project to build an automatic window for the greenhouse.

The session at the Science Center was worthwhile. All of the students seemed to enjoy it. It provided a nice integration of the mechanics and electronics we’ve been learning about all year, and a glimpse of where technology is taking us in the future.

Physics and history in Vicksburg, MS.

Salvage of the ironclad, USS Cairo, in Vicksburg National Military Park.

Four hours away, Vicksburg, MS. is just within reach for an immersion trip so, since we were in the area, I scoped it out for a future trip. Vicksburg was the final town to fall before the Union could control the Mississippi River and split the Confederacy into two, so it’s historically important. The Vicksburg National Military Park is chock full of monuments and markers that give a good idea about the chaos and carnage of the battle for the town, and even a chance to observe practical application of simple machines and steam engines.

The park could complement Shiloh and Corinth quite nicely since Vicksburg’s importance was because of its control of transportation routes, just like with Corinth. It also has the salvage of the USS Cairo, an ironclad sunk during the Civil War. Much of he Hull is still missing so it’s a wonderful chance to see all the mechanisms and engines in a steam powered ship.

watermill2 — Watermill at Grand Gulf Military State Park.

What I found most interesting, however, were the old watermill and farming equipment at Grand Gulf Military Park, about 45 minutes south of Vicksburg. They seem almost in working order, and if you’ve been discussing simple machines, as we have, it’s a great opportunity to see how they were applied in real-life.

sub-and-still — One-man submarine with bootlegger's still in background.

The watermill is quite picturesque, making it a great subject for sketching or drawing. I like to combine art and science in this way when possible. Grand Gulf also has a small, submarine used by bootleggers during prohibition which is quite the curious piece of engineering.

[googleMap name=”Grand Gulf Military State Park” description=”Watermill and camping” width=”400″ height=”300″ mapzoom=”8″ mousewheel=”false”]12006 Grand Gulf Rd, Port Gibson, MS[/googleMap]

Methane hydrates for energy

Despite the fact that methane is a powerful greenhouse gas itself and burning it produces carbon dioxide there is currently quite a bit of research on extracting methane hydrates from the sea floor as an alternative to the traditional fossil fuels because there is just so much of it. Discovery Channel has an interesting video on the topic where they burn some methane hydrate ice.

Methane releases from the arctic and sea-floor could also trigger rapid climate change. Recent discoveries suggest that global warming is warming the arctic so much that the permafrost is melting an releasing a lot of methane into the atmosphere. If the arctic atmosphere continues to warm, more methane will be released, causing more warming …. This positive feedback loop would accelerate global warming. Some scientists worry that warmer ocean waters can melt methane hydrates at the sea floor releasing them into the atmosphere in a similar positive feedback loop.

Corinth Mississippi in the Civil War

corinth-stream — Stream of American History at the Corinth Civil War Interpretive center.

The Memphis to Charleston line was the only railroad that linked the East Coast of the Confederacy to the fertile Mississippi River Valley. At a time when the fastest way to move troops, supplies and commerce was by river or rail, the Memphis and Charleston railroad was essential (this was well noted in Robert Black’s “The Railroads of the Confederacy”). Cutting the railroad was an important objective of the Union. Cutting it at Corinth Mississippi would also cut the Mobile and Ohio Railroad line which linked the north and south of the Confederacy. Thus the Battle of Shiloh, where the Union could disembark its armies using the Tennessee River, and soon after, the Battle of Corinth.

The Civil War Interpretive Center in Corinth (this is also a good reference) does a nice job of presenting the details of the battles for the town, and their video presentation, with different images projected on multiple screens in a circular room was quite good (though there was a lot of information and you did not know quite which screen to focus on, so some students had trouble keeping track of it all).

standing-wave — Standing waves: turbulence in the stream of American history.

The most interesting part of the center is the Stream of American History which is a wonderful place to learn about metaphors. The stream starts with a fountain that overflows through 13 notches cut in the rim of the basin into a shallow water course that gradually widens as more states are added to the U.S. In the first reach of the stream there are impediments in the paved stream bed that create turbulence, harbingers of the war to come (they create nice standing waves which is an additional point in their benefit).

When the stream gets to its main focus, the civil war, large granitic blocks, cut into prisms and labeled with the names of the battles, break the stream into two before it finally merges again as it reaches the reflecting pool.

I threw my students at the Stream without telling them what it was. The only hint I gave was that it was a “large metaphor”. There were enough clues that they could figure it out. They wandered around it individually, with their pencils and notepaper for 15 minutes (I required that they write down their interpretation, then we got them together to pool their thoughts.

The stream is a very nice puzzle, and the National Park Service has a good key (pdf). It was a good way to end our immersion trip, and it gave the students something to think about on the long drive home.

[googleMap name=”Corinth Civil War Interpretive Center” width=”400″ height=”350″ mapzoom=”4″ mousewheel=”false” directions_to=”false”]501 West Linden Street, Corinth, MS‎[/googleMap]

Pickwick Landing Hydroelectric Dam

[googleMap name=”Old Turbine” description=”Pickwick Landing Hydroelectric Dam” width=”490″ height=”490″ mapzoom=”14″ mousewheel=”false”]35.072711, -88.250578[/googleMap]

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.

pickwick-locks — Barge exiting the lock.

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.

About The Elegant Universe

NOVA’s program The Elegant Universe has an excellent website where the entire three hour video is available for free (with a full screen option). They have also broken the video up into segments and have a great teachers’ page which summarizes what’s in each segment.

Created in 2003, when string theory was making it’s big splash in the popular consciousness, The Elegant Universe starts with Newton’s observations of gravity, shows Einstein’s separate explanations of why gravity works and the nature of the sub-atomic world, and finally delves into string theory which tries to reconcile Einstein’s two theories into a unified whole.

We don’t usually get past Newton in middle school, but this PBS program introduces such a wider and weirder view of the universe that it can help strike the imagination. It also presents complex concepts in an intelligible way.

Build your own generator

If you don’t have a generator building kit, but do have a few magnets, some wire and a long nail, you can build your own generator using the instructions on William Beaty’s website, ‘Ultra-simple Electric Generator‘. The video gives excellent, detailed instructions, but there are also written instructions with a supplies list.

UPDATE: A small group of my students tried this and, despite the complaints, I thought it was a useful exercise. I’m looking forward to their presentation tomorrow.