Lensyl Urbano – Page 125 – Montessori Muddle

Epic Rain-Garden

flowerbed-angels — They're making dirt-angels, actually.

Talk about a long day! (“What an understatement,” she says.)

flowerbed-before — The 'before' picture.

We moved about 45 tons of sand, gravel and compost today, filling in the moat we dug last week. We were lucky enough to have the help of a backhoe for the digging, but all the filling in today was done by hand, with shovels and wheelbarrows.

flowerbed-night-backhoe — Digging the moat.

Despite rumors about it being a first line of defense against the Cordovan barbarian hordes, the moat was actually intended to become a rain garden, which was designed by the Rhodes College Hydrogeology class to intercept some of the runoff slope that funnels water directly down toward the school during the intense rainfall that we get with our spring and fall mid-latitude cyclones.

So we had to get rid of the heavy, dense, silty-loam soil that is really slow to let water seep through, and makes it hard to grow anything on the Memphis side of the Mississippi River. The fine grained silt was blown over from the Mississippi River floodplain about 20,000 years ago when the ice-age glaciers were melting and all their ground up rock flour was being washed down the Mississippi. This type of wind-blown sediment is called loess. I like the sound of the word because if you stretch out the “oe” properly it does something to the back of your throat that feels distinctly German; however, if you ask someone from the deep south to pronounce it, you’ll hear the name of Clark Kent’s girlfriend.

flowerbed-sh-oil — Middleschooler pushing a wheelbarrow full of silty-loam.

The backhoe dug two trenches, each about 2 m wide, 6 m long, and about 60 cm deep, and piled the soil up next to the holes. Moving this stuff is not trivial. My middle-school students gave it a try on Friday afternoon and though they made a small dent, there is an awful lot more to do (my students also helped figure out how long it would take to finish pumping out Friday morning’s collected rainwater from the trenches).

flowerbed-pea-gravel-delivery — Five cubic yards of pea gravel.

Then, on Saturday, with large piles of the old soil still sitting there, we replaced the impermeable loam with a fifty-fifty mix of sand and compost, underlain by five centimeters of pea-sized gravel on top of five centimeters of crushed limestone. This material was delivered by dump truck on Friday afternoon, while school was still in session. It was loud, exciting, and according to one member of the pre-school aged audience, “the best day ever!”

flowerbed-best-day-ever-oil — Enjoying the 'best day ever.'

I have to agree. It was kind-of exciting. Although for me, the bright, brown pile of pea gravel evoked fond memories of pyramids of powdered curry, saffron and tummeric sitting on the spice-seller’s stall in a market in Morocco .

flowerbed-pea-gravel-therapy-1 — Rhodes students slacking off (after lugging soil and gravel all day).

For others the pea gravel was a more tactile experience: snuggling into it, after a hard day’s work, appeared to be quite therapeutic.

flowerbed-pea-gravel-therapy-2-oil — Girl Scouts taking a well earned break.

flowerbed-pea-gravel-therapy-3 — Middle school students slacking off (after ...?).

flowerbed-hauling-dirt — Hauling silty clay.

flowerbed-wading — Dr. Jen raking in the first of the gravel in the not yet drained pit.

flowerbed-team-ziebarth — Team Z. on the top of the mound.

flowerbed-gravel-tossing — Gravel tossing.

flowerbed-job-well-done — The last of the pile. Job well done.

To be continued…

It’s 10 PM and the Moat is Empty

My students and I had a great chance to use the our recent geometry work when we figured out how long it would take to drain the new moat in front of the school.

It’s not really a moat, it’s going to be a flower bed that will soak up some of the runoff that tries to seep into the school’s doors every time a spring or fall thunderstorm sweeps through.

The hole was dug on Thursday evening and filled with rainwater with water, half a meter deep, by Friday morning’s rain. At least we know now that the new beds are in the right place to attract runoff.

But to fill the trenches with gravel, sand and soil, we needed to drain the water. With a small electrical pump it seemed like it would take forever; except that we could do the math.

The pump emptied water through a long hose that runs around the back of the building where the topography is lower. I sent two students with a pitcher and a timer (an iPod Touch actually) to get the flow rate.

They came back with a time of 18.9 seconds to fill 4 liters. I sent them back to take another measurement, and had them average the to numbers to get the more reliable value of 18.65 seconds.

Then one of the students got out the meter-stick and measured the depth of the moat at a few locations. The measurements ranged from 46 cm to about 36 cm and we guesstimated that we could model the moat as having two parts, both sloping. After measuring the length (~6 m) and width (2 m), we went inside to do the math.

moat-volume — Rough sketch of the volume of water in the moat.

With the help of two of my students who tend to take the advanced math option every cycle, we calculated the volume of water (in cm³) and the flow rate of the pumped water (0.2145 cm³/s). Then we could work out the time it would take to drain the water, which turned out to be a pretty large number of seconds. We converted to minutes and then hours. The final result was about 7 hours, which would mean that the pump would need to run until 10 pm.

And it did.

Art and Science: Flow Paths

I’ve been helping my wife model the fluid flow through her apparatus, and she has some really neat results from some experiments where two chemicals react and block off the regular, symmetrical flow.

The streamlines look a bit like butterfly wings to me, so I modified the image a little. The original flow paths through the circular apparatus are below. I’m not sure which image I like better.

P.S. The other thing I learned from this little exercise is how to write Scalable Vector Graphics (svg) files (W3C has an excellent reference). With svg’s, like other vector graphics formats, no matter how big you blow them up you never loose resolution like you would do with a regular, rasterized image. Unfortunately, I still have to figure out how to include the svg files on this blog, so these png images will have to do for now.

The Moral Dilemmas of High-Stakes Tests

Just in time for the standardized testing season, Gillum and Bello have a damning article on irregularities in the testing at some Washington D.C. schools. NPR has a good summary of the situation and the investigation.

Sadly, with the fates of their schools and their jobs depending on the outcome, the faculty and staff administering these tests to their own students face an unfortunate conflict of interests and are placed in a serious moral hazzard. It’s also not hard to imagine the potential for ramped-up pressure on the students.

Standardized tests can play an important role in maintaining quality in the vast network of schools that make up the US’s educational system. They also help maintain consistency, of which a certain amount is probably good, but can be awfully restrictive. But the most unfortunate aspect about the way they’re actually used, is that they create intense pressure on students and faculty that is deleterious to student performance on the tests themselves, and severely restricts the way students think about what it means to learn.

Guide to U.S. Geology: For Teachers

se_regions3 — The Coastal Plain, one of the three major geologic provinces of the southeastern United States. From the Teacher-Friendly Guide to the Geology of the United States (Picconi, 2003).

J.E. Picconi, from the Paleontogical Research Institution, has a nice website that describes the geology of the different regions of the U.S..

sandy2 — This image shows the low-energy, offshore environment of the grey shales like that of Coon Creek. From Picconi (2003).

The site has a nice clean design, and is readable to anyone with a basic grasp of geology and geologic time.

I’ve looked at the the section on the southeastern U.S., which even a section on the different, official state fossils.

I particularly like the icons they use to show the environments in which the different fossilized organisms once lived.

The Gimp: Photoshop’s Free Cousin

For those of us too cheap to buy Photoshop, or who want to support the open-source movement, the Gimp is a great little image manipulation program. I use the “Oilify” option a lot to obscure students’ faces. Gimp’s not as sophisticated as Photoshop, but if you’re not heavily into graphic design, and are not too picky, it does a good job.

jumping_the_ditch0539-c — Jumping the creek. Be careful with the flaming sword; someone might get hurt. (Image created by Piper Ziebarth; photographer Lensyl Urbano).

As a Photoshop clone, Gimp shares many of its basic principles. It also comes from the ImageMagick command line tools, which I’ve used to automate image processing in the past.

Gimp itself is, however, pretty easy to learn. I’ve shown one student how to use it, and we’ll see if and how the knowledge propagates through the class.

nt-sh-crossing-the-stream-b — Triplets? Clones? Or maybe robots?

Global Warming: We need new colors.

hansen-pink-T — These maps show the difference between last winter's average temperatures and the long term average (from 1951-1980). Notice that the scale goes up to 11. Image from Hansen and Sato, 2011.

For much of the U.S., last winter was pretty cold. If you look at the maps above, you can see that the eastern United States was up to 4 °C colder than normal in December. However, if you look a little further north into Canada, you’ll see a broad, pink region, where the temperatures were up to 11 °C warmer than normal.

The rate at which the world has been warming has been accelerating. It’s been interesting watching the predictions of the relatively crude computer models of the 1980’s coming true.

Although, it’s really the broadest, more general predictions that tend to be more reliable. One of those predictions, that’s been consistent for a long time and with a lot of different models, is that the poles would warm significantly faster than the rest of the planet.

What’s also been interesting, if somewhat depressing, is seeing the political consensus lag behind the scientific consensus. Twenty years ago there was a real debate in the scientific community about if global temperatures were rising. Now scientists argue mainly about what to do: reduce greenhouse gas pollution, adapt to the inevitable, or some mix of the two. Yet two weeks ago the House Science Committee heard testimony from a professor of marketing, advocating for an end to all government funding of climate research. Perhaps the belief is that if we don’t look it won’t happen.

Curiously, even research teams funded by people who politically oppose global warming, are just confirming the results of all the other scientific groups. Unsurprisingly, they’re now getting heat from their former supporters.

At the same time, Kate (on climatesafety.org) observes that NASA’s James Hansen has had to add a new color (pink on the graphs at the top of the page) to his climate anomaly maps because of the unexpectedly large warming over last winter.