Dill flowers are pretty enough in real life, but look really interesting under the microscope as well. So I put a few pictures from my time with the Leica DSM1000b into the online microscope:
Month: July 2013
Understanding the Extinction of the Dinosaurs (and the Survival of Mammals)
This neat paper (Robertson et al., 2013) in the Journal of Geophysical Research makes an interesting attempt to explain the pattern of extinctions that occurred at the end of the Cretaceous: why most of the dinosaurs died out, and why ocean organisms were more severely affected than freshwater organisms by the long winter after the asteroid impact.
The flow chart explains:
They also include an interesting figure showing how long an organism might survive based on how large it is, which I may be able to use in pre-Calculus when we’re discussing log scales and linearizing equations.
![Allometric relationship between body size and time to death by starvation for multicellular poikilotherms in the absence of food (red, drawn from the equation of Peters [1983, p. 42]). Names of various types of organisms are shown as an indication of body size. Image and caption from Robertson et al., 2013.](http://MontessoriMuddle.org/wp-content/uploads/2013/07/Robertson_et_al_2013_Fig1.png)
The article is written well enough that an interested high school biology student should be able to decipher (and present) it.
Crayfish: Charismatic Mesofauna
This year, the creek is teeming with crayfish, especially compared to last year during the drought when the creek dried up and the crustaceans were hard to find. I had five students out collecting organisms on Wednesday, and they came back with ten crayfish ranging in size from a couple centimeters long, to one that was about 12 centimeters from claws to tail.
I was just looking at one of the pictures I took and realized that I did not know what species it belonged to. I’ll be having students do reports on individual species for biology next year, and I’d be very surprised if someone did not choose crayfish. They’re so many of them and, as my students from Wednesday will attest, they’re just so charismatic. While I’ve not looked into it much myself, the Crayfish & Lobster Taxonomy Browser seems a decent place to start researching.
A Tadpole with Legs
Among the interesting things we collected from the creek yesterday, was a tadpole that was in the process of developing legs.
This is particularly interesting since we’ve had a tadpole in our fish tank since last fall that still has not shown signs of transforming.
3d Molecule Viewer
An excellent 3d viewer for molecules.
In addition to the existing molecules, you can import any number of others if you can find them in one of the right formats (PDB, SDF or MOL molecule definitions): the ligand.info: Small Molecule Meta Database is a good source for SDFs.
Johnson’s Shut Ins
First off, the Shut Ins are narrower constrictions in the river valley formed when stream flows into an area of harder rock. The hard rock, in this case an old (1.5 billion year old) rhyolite flow, is relatively resistant to erosion, especially the side-to-side erosion that flattens out little flood plains as small rivers meander through the foothills of old mountains like the Ozarks. So the stream only erodes downward through the hard rocks creating a narrow gorge. As they say here: the river’s “Shut In”.
When I told people that I wanted to do a few camping trips this summer, the number one recommendation was the Shut Ins. And I can see why. I took my boys and they had an awesome time.
“It’s like the City Museum. Only real.”
— Overheard at Johnson’s Shut Ins
The Shut Ins are a maze of narrow channels, the old igneous rocks carved smooth by the water and its gravelly bed load over millions of years. A great place for kids to traipse through and explore. I bit like a water-park version of the City Museum in St. Louis.
The pattern of the channels is largely determined by the jointing in the rocks, because the joints offer easier pathways for water and erosion. There are at least two obvious sets of joints in the rocks, but I would not be surprised if they overlay other patterns given how old the rocks are. As it is, however, the erosion through the joints creates lots of neat little chutes.
Since the Shut Ins are only a couple hours away from St. Louis, they’re a pretty popular tourist attraction.
There’s a lot of science that can be done here, however, that would make this a good location for an immersion trip, especially since Elephant Hills State Park (with wonderful spheroidal weathering) is close by. The camping facilities at the Shut Ins State Park are new and quite nice, having been completely rebuilt with some of the $100 million in settlement money from the Ameren power company after the park was flooded by their Taum Sauk reservoir breach in 2005.
It’s certainly worth the visit.
Teaching with the Hands
Doug Stowe is an artisan who specializes in making small boxes. He also teaches woodworking and records his thoughts on the melding of education and craftsmanship on his wonderfully reflective blog, Wisdom of the Hands. For example:
In his introductory remarks published in the Teacher’s Hand-Book of Educational Sloyd, Salomon notes the difference between a trained artisan and a teacher. While the trained artisan is focused by necessity on the qualities inherent in the finished product, the teacher must be concerned with the qualities developed within the child. An artisan might step in to make sure the child gets the work right, while the teacher might step back to see that the child learns. In other words, the predisposition of the artisan vs. teacher may be leading in completely different directions.
— Doug Stowe: beyond craftsmanship on Wisdom of the Hands (blog).
I really like the core message here. I’m an advocate for apprenticeship learning: how better to learn to think and act like an experts. But the key lesson for the expert is that students need to be given the opportunity to experiment, and even to make mistakes, in order to learn.
After my own, rough, experiments with making a slide holder, I’d love to take a lesson from someone who knows what they’re doing.
P.S. Hat tip to Karin Niehoff of the Crescent Montessori School for the connection.
Constructing a Wooden Slide Tray
To have somewhere to store the slides I’ve been making, I needed a slide storage box. They’re pretty cheap, but they’re also pretty simple to put together with stuff I could, mostly, find around the house: some scrap wood (from an small wooden CD holder tray that I’m not using any more); a small sheet of clear acrylic (from the hardware store); a short piece of sticky-backed, rubber foam for insulating windows (to keep the slides pressed into place so they don’t move in the box); and some craft glue (ModPodge). For tools, all I used were a few clamps and the saw on a pocket tool.
Using the pocket saw was the biggest pain because I had to cut little slots into the wooden frame to hold the slides. Twenty five slides meant 50 slots, and although the wood was soft, the width of the blade was almost exactly the width of a slide, so if the slot was not perfectly vertical the slides would not fit properly and I’d have to carefully saw it a little bigger. The clamps were a big help with the sawing.
