Saturday, December 28, 2013

Favorite comments of '13, cont: Anonymous, ChemProf, and Auntie Ann

On The beauty of armchair science

Anonymous said...

To the extent that the hands-on experience is valuable for K-8 students, I think that showing them some basics through observation goes a lot farther than experiments do. Especially for kids whose home lives don't provide any observation of the natural world in an organized way. I have found kids who don't realize, for example, that trees started out as little seedlings. Why would they? at 6, they haven't been around long enough to see that happen. Also, kids who don't realize that some birds fly south and other don't. Kids who have no sense of where food comes from. And so on. These can be taught very efficiently through guided observation, hopefully not too far from the school building. And field trips should focus on this aspect of science too.
ChemProf said...

Experiments can be really helpful, but the most helpful for learning are usually guided observations. Even in college, this is often the case (although the observations can look different). For a long time, we'd struggled with teaching gas laws to students, who didn't have any intuition about how gases behave under different conditions. Adding a very simple lab where students observed the pressure of air in a gas tight syringe (so they could change the volume easily) made those problems disappear. But having a "discovery" lab where students flailed around blindly (and that's what is often meant by lab experiences in K-12) wouldn't have had the same impact.

Anonymous said...

Right, Chemprof. The chemistry lab experiments we did in HS were totally scripted; we did not design experiments (though we did have to figure out how to represent the results in terms of standard chemical notation). I think the real point was to get us comfortable with using lab equipment so it wouldn't trip us up in college. But we did not really learn anything new in the lab, we just demonstrated to ourselves material we had learned.

ChemProf said...
Chemistry is different from physics, in part because a chemist should have a set of skills as well as theoretical knowledge. If you can't prepare a standard curve or do a titration, you aren't really a chemist. It is actually a problem in my field that the practical has been undervalued at a lot of schools -- it is easier to hand the sample to the TA when there are hundreds of students, but then students graduate without the hands on experience they should have.

Auntie Ann said...

As a physics major and later in engineering, I never enjoyed labwork. When working on some of the more expensive equipment (like a low-energy particle accelerator,) I was always afraid I'd break it. With the exception of a couple labs during my waves class, most were forgettable.

I don't remember ever coming to any realization during lab work, nor did I need the tactile experience to understand most of the concepts. With physics, much can be grasped perfectly well in the abstract or through every-day experience.

For K-8, some things a kid should do:

-- Look at various things under a microscope, sometimes with dyes. Cells, both plant & animal. Crystals, salt, sugar, etc. Pond water with small organisms. Every-day items: hair, cloth, paper, pencil lead, wood, etc.

-- Do acid/base experiments.

-- Basic battery & current experiments. Completing/breaking a circuit.

-- Gravity experiments: dropping, pendulum, etc.

-- Weather observation; during one day, during seasons.

-- Star charting to see change during year.

-- Observations of the phases of the moon.

-- Usually get a shot at least one partial solar eclipse every few years. For that one I love to walk under a tree; the little gaps between the leaves act as pin-holes, and the ground becomes covered with the crescent of the sun.

-- Grow a plant from a seed.

-- Some cooking science: yeast, baking soda, caramelization, etc.

-- Then just measuring things using different tools: mass, length, volume, time. 


gasstationwithoutpumps said...

A good engineering lab is very different from a freshman physics or chem lab. The physics and chem labs are intended just to provide certain lab skills and reinforce a concept that should have already been learned though problem sets.

A good engineering lab should be a design lab—it should have the form "design, build, test, and document something that does X". The tricky part in devising such labs is to make the design easy enough that students can do it, but challenging enough that there is a genuine sense of accomplishment when it is achieved. Students should leave an engineering lab feeling that they can do things that they didn't realize before that they could do.

It is really hard to devise such labs, so many engineering labs end up being cookie-cutter labs like the chem and physics intro labs—a shame, really.

You can find 100s of pages of my attempts to design a course around design labs in

ChemProf said...

Sure, but that works because students already have a lot of other lab experience. I do something similar with my juniors in Analytical Chemistry -- they have to come up with a "measure x in y" experiment, develop a procedure, do the experiment, analyze the data, and write up a report. They find that two weeks (~10 hours) is often barely enough time to start, and they are just figuring out what they should have done differently at that point. An example -- a student measuring zinc in sunscreen found her extraction was incomplete because the zinc was suspended in beeswax which didn't dissolve well. For the juniors, it is a really good experience, but for first years it would just be frustrating.