Author: enricouva

Sex Ed and Physics

EmbraceFor at least one year, our school did not offer a separate course-section in human sexuality for adolescents. We were told to integrate it into whatever we were teaching. Not surprisingly, this got people’s backs up. Some courses and sex ed simply do not mix, it seemed. How, for example, can you integrate sexuality and basic physics?

 

220px-CoulombsLaw.svg
From Wikipedia

Maybe there is a way.

Maybe, by using the terminology and concepts of physics there is a way you can shed light on human sexuality by pointing out what it is not.

Sexual attraction is not Coulombic. It is not necessarily between opposites; it is not always proportional to the amount of charge; it does not have to vary inversely with the square of separation-distance between charges.

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The Craft of Teaching

teachingmeme1This meme appeared on a teachers’ Facebook group called TeacherGoals. Predictably, within 11 hours, it gained 900 likes among its 159 000 followers .

The saying is something I’ve heard often throughout my teaching career. Variation of approaches is at the disposal of every experienced teacher, who will use them successfully.  But as is the case with political views, it’s best not to feel smug or, worse, superior to someone else merely for adhering to a particular idea.

For instance, contrary to what is being promoted in this case, the same delivery could work the second time around if

(1) the lesson is delivered more slowly

(2) the teacher or student is not as tired

(3) if there are less distractions

(4) if the concept needs a period of incubation, which is often the case, and so on.

As usual memes oversimplify everything. They’re better at boosting Facebook’s revenues than at advancing pedagogy.

Here are a few guidelines and strategies that teaching colleges, certification boards and professional associations might find useful to better train science teachers. Some may seem obvious to the outsider, but you’d be surprised how seldom they are implemented. And, of course, our students get shortchanged.

(1) For high school math and science, a teacher should have at least a bachelor’s degree with a major in the main subject they teach. This not only increases the likelihood that the potential teacher’s basics have been reinforced, but it gives him an inkling of where a particular concept or skill can lead. Equally important, knowing that he is only scratching the surface of his subject, the teacher with a better background can be more convincing that the very basics are within anybody’s reach—as long as there’s a bit of an effort on the part of both the student and the teacher.

(2) Work experience related to the subject is more of an asset that some people realize. Working in three different analytical labs gave me a lot of practical skills that came in handy in managing labs and keeping better standards for my students. Ideally, occasional work terms should replace so-called “professional development”, which often amounts to little more than exposing teachers to sales pitches from educational industry representatives or to people promoting the latest flavour of the year in pedagogy.

(3) Student teachers do not have to be sent into the field for the very long periods that have unfortunately become customary. Given that most student teachers are not as effective as most experienced teachers, a large chunk of the high school student’s course is compromised. As an alternative, student teachers can prepare several lessons and lab activities for other student teachers while being filmed. Peers along with the supervisor and student teacher can then view the films and give constructive criticism.

(4) The most common role model for human beings is the electron because most people choose the path of least resistance. If, by setting an example, a teacher can prevent at least some of his students from imitating the negatively charged constituent of matter, he will have taught them one of life’s most valuable lessons.

 

 

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Thirteen (mostly) Chemistry Demonstrations in 280 Characters Or Less

  1. Ground #helium balloons with a bunch of grapes. Then remove 1 grape at a time until the buoyant & gravitational forces balance out. The balloons will be suspended in the air. Children quickly catch on and have injected a little #science into an otherwise dull wedding reception.
  2. Add copper to HCl & watch nothing happen. Add Cu to HNO3, & NO2 or NO forms, depending on the acid’s concentration. Add CuO to citric acid, wait a few days & a (patina-like?) material forms.
  3. ZNO44To a beaker, add sand and a 50% solution of methanol. Then add spatula tips of zinc oxide powder. Close lights. Transitions are very temperature-dependent and different parts of the flame create a variety of colors. Students prefer demo to drugs.
  4. Add calcium to water & phenolphthalein. Collect H2. Ignite it. Color change in solution reveals hydroxide formation. White precipitate of CaO settles below fuchsia solution. Filter it. Blow into solution of Ca(OH)2 to form CaCO3. More CO2 forms acid, gets rids of cloudiness.
  5. ammoniaAdd 2 drops of bromothymol blue to a (pH ~ 4) solution in a flat-bottomed flask. Add dilute NaOH to beaker. Bring the flask to a boil for 3-5 minutes. Remove heat source & wrap a cold, wet rag around the flask. Be awed by work of ΔPV.
  6. Get a hand-held digital microscope. Use it to reveal  the sensuous surface of a grapefruit, an aborted seed; and the oxidation of copper in an old penny. 

SANYO DIGITAL CAMERAChip off 5 samples from a boulder. Use water displacement in large cylinder to find the volume of each piece. Mass each rock. Obtain average density. With latter & an estimate of the boulder’s volume, get an estimate of the boulder’s mass.
8. Get a thin flow from a water tap. Wrap cotton shirt around a plastic comb. Rub it. Move the comb towards the water without touching it. Watch the stream bend like a banana. Water is neutral, but something charged within it is attracted to the oppositely charged comb.Static 9. Demonstrate that old pieces of magnesium often won’t flash in a Bunsen burner flame. Their surface has reacted with air. Wipe a piece with a paper towel that’s wet with dilute acid. Dry, weigh, ignite& look away! After it flashes, reveal that white residue’s mass > than original.
10. CO2Add two drops of bromothymol blue to 4 different test tubes containing tap water. Add distilled water to the 1st; it remains green. Add baking soda to 2nd, get blue. To the 3rd and 4th add vinegar & dry ice (CO2). Both go yellow as both additives lead to H+.

11. Ignite a hydrogen-filled balloon. Note red color from excess H2 incandescing in heat of reaction. Fill a 2nd balloon with 2:1 ratio of H2 to O2 & ignite; observe no red color. Fill 3rd balloon with hydrogen and add a little copper sulfate. Explosion becomes green-colored.

12. Spread a few grams of iron filings on a filter paper. Place it a magnetic stirrer. Turn it on at medium speed. A beautiful display of a magnetic field in motion ensues. It resembles a living colony of microorganisms.

13. The calcium carbonate in blackboard chalk is long-baked, so it quickly settles, and more stays out of the respiratory system. Yet, if you examine any ledge or border high above the board, it fills with chalk dust over the school year. How? Brownian motion.

14. Imagine someone you has wronged you. Imagine taking a wet sheet of newspaper& sticking it on the guy’s windshield on a cold day. Due to H-bonding he’ll never be able to scrape it off, unless he has access to hot water. Imagine writing on the paper, “Revenge is best served cold.”

More to come.

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