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.

ᔥ The Dish

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).

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.

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.

I’m really beginning to like the idea of giving students the option of putting together their own, individual, slide collections. So, to practice mounting slides with nail polish, I tried to make a start on my own permanent slide collection. It was partially successful.

Procedure

To start, I found a dead fly near the window. It had been dead for a while and so I assumed it was pretty well dried. Carefully, under the stereoscope, I pulled off the appendages — antenna, wings, legs — for mounting. The fly itself was too big to mount, as were the major body parts, but as I was dismembering it the head, thorax, and abdomen came apart. In fact, the head broke into a few pieces as well, including one of the compound eyes, which I thought would be worth trying to mount even though it was somewhat thicker than the other parts.

I started with the antenna. The procedure I tried to follow is simple. Place a small drop of nail polish on the slide and then put the sample on the nail polish drop. Next place a drop of nail polish on the coverslip, flip it upside down and put the two drops together. The weight of the coverslip will flatten nail polish out into a thin layer. You then put small drops of nail polish at each corner of the coverslip. The polish will seep in between the slide an coverslip by capillary action until the entire underside of the slip is saturated.

Since the antenna was so small, I actually broke a cover slip into quarters to make them, I hoped, easier to manage. The slides were then left to dry overnight.

The initial results were, as I have mentioned, mixed. Bubbles encroached on a number of the specimens, particularly the thicker ones, like the rear legs, but for the most part, the specimens were clearly visible, with a minimum of obstructions to the view.

Antenna

Antenna at 40x magnification:

Antenna at 100x magnification:

Antenna tip at 400x:

Legs

Of the four leg slides I made, three had serious problems with bubbles, and the one that did not was missing the end segment of the leg. Part of the problem with the bubbles may have been that it took me a while to get the legs onto the nail polish drops, which allowed the drops time to evaporate. This could have resulted in a more viscous drop by the time I added the coverslips, which would not have lain down quite as flat, leaving space for the bubbles to come in. Another possibility is that the thickness of the legs made the glass coverslip tip up toward one side.

Fly front leg:

Middle leg:

The tip of the middle leg is inside the nail polish.

Rear leg:

Rear Wing

The last appendages I mounted were the two small, rear wings. They were very thin and I placed them both under the same full sized slide. It worked quite well.

Rear wing at 40x:

Rear wing at 100x:

Rear wing at 400x (focus stacked):

Fly Eye

The eye came out remarkably well.