I took three students to a workshop were we’re building a 3d printer. It’s run out of the Whitfield School. We spend today putting together the electronics to run the five motors we need to get the thing to work, and starting to put the frame together.
The frame is based on the RepRap Prusa i3 (via DIY Tech Shop), and the plastic parts that hold the rods, electronics and other metal bits together are 3d printed themselves.
Students learn to solder.
The motors is run by an Arduino, which is great because I’ve been thinking about using one to operate the doors to the chicken coops.
Vicki Davis has a nice compilation of resources for teaching coding to kids of all ages. Of the fifteen things she lists, the ones I’ve used, like Scratch and the Raspberry Pi have been great.
As noted previously, the Finns have no homework, while the South Koreans have a lot. Yet these two countries’ educational systems are ranked 1 and 2 in the world. Misty Adoniou summarizes some of the research into the effectiveness of homework.
A key point: there are two types of homework, neither of which may be awfully useful:
Extra-practice: Which sometimes does not help a lot because often parents don’t have the expertise to give help when needed.
Creative extensions: Which students don’t necessarily need or enjoy because they’d prefer to come up with their interesting projects — if they did not have all the homework (or other distractions).
The type of homework I assign differs by subject. For science, I’ll often ask students to do reading assignments and make vocabulary cards before we cover a topic in class. It’s to give them a little preparation and, theoretically, allows us to do more higher-level, application type projects in class–this is the same as the idea behind flipped classrooms. For math, the objective is for students to get extra practice. Much of algebra and calculus relies on pattern recognition–when you can use integration by substitution for example–so some students benefit from extra practice after class.
The amino acid methionine, aka 2-amino-4-(methylthio)butanoic acid.
During the last interim, we paid a visit to Novus International, a large, multinational, animal nutrition company. And now that we’re talking about proteins in biology, there’s some extra relevance because students are aware of Novus’ major products that are precursors to the amino acid, methionine (they sell about a billion dollars a year).
Solid and liquid forms of the methionine precursor MHA.
I particularly liked the set of speakers they chose for us, because they covered such a broad span of the company: from business, to marketing, all the way through to the science. They also gave us a tour of their highly energy efficient building, and grounds that they’re landscaping with native plants and vegetable gardens.
It was definitely a worthwhile trip. Thanks to Ms. Mertz for arranging it.
Ms. Mertz’s biology class chased water droplets around a piece of wax paper to study the properties of water. It was pretty neat how she had them name the droplets and then use a toothpick to drag them around, join them up, and split them apart.
Dragging water droplets around a piece of wax paper using a wooden toothpick.
The water sticking together to form droplets is due to the hydrogen bonding between the water molecules: each water molecule has a slightly positively charged end and a slightly negatively charged end that causes molecules to stick together.
Hydrogen bonding among water molecules is due to the shape of the individual molecule. Since the molecule is “bent” one end has a slightly more negative charge and the other a slightly more positive. Image by User Qwerter at Czech wikipedia.
The ability to drag the water droplets around using a toothpick is because the cellulose fibers in the wood have their own slight charges that make them hydrophilic.
The students then tried dragging the water droplets around using a small piece of plastic straw, which was not supposed to be hydrophilic. However, it was a little hard to tell the difference between the straw and the wood. We’re not sure why, so we’ll have to revisit that part of the experiment again.
Ms. Mertz followed up with another nice little demonstration of the effect of soaps on water. She sprinkled some black pepper onto the surface of some water in a bowl, and then took a toothpick, dipped it into a bottle of liquid dish-washing soap, and then dipped the tip into the center of the bowl. The result was quite immediate, and quite dramatic.
A bowl of water with black pepper floating on top, just before dipping in the soap covered toothpick.After dipping in the soap covered toothpick.
The soap molecules are forced to form a thin layer on top of the water as their charged end is pulled down toward the water and their uncharged, hydrophobic end is pushed away.
Over the weekend I ran into this article from Planet Money/This American Life about a charity that just gives money directly to people. It should help to prepare my students for the Heifer International Ranch trip next month. It’s interesting to hear what people spend the money on; things like metal roofs and cows. Heifer gives cows and training instead of just cash. The article compares and contrasts the two approaches.
