Entries Categorized as 'Uncategorized'

Methionine: A Visit to Novus International

November 16, 2013

The amino acid methionine, aka 2-amino-4-(methylthio)butanoic acid.

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.

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.

Novus' metaphorical metal cow.

Novus’ metaphorical metal cow.

Citing this post: Urbano, L., 2013. Methionine: A Visit to Novus International, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Chasing Water

October 15, 2013

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.

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.

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.

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.

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.

Citing this post: Urbano, L., 2013. Chasing Water, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

How to Give Effectively

August 20, 2013

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.

Citing this post: Urbano, L., 2013. How to Give Effectively, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Insect Appendages: Practicing Mounting Specimens

July 1, 2013

Microscope slide with fly antenna mounted in nail polish.

Microscope slide with fly antenna mounted in nail polish.

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

The subject fly. 30x magnification under the stereoscope.

The subject fly. 30x magnification under the stereoscope.

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:

Fly's antenna at 40x magnification. Mounted in nail polish: Strengthener, Nail Hardener. Notice the air bubble encroaching on the sample from the bottom.

Fly’s antenna at 40x magnification. Mounted on slide in nail polish: Strengthener, Nail Hardener. Notice the air bubble encroaching on the sample from the bottom.

Antenna at 100x magnification:

Fly antenna tip at 100x.

Fly antenna tip at 100x.

Antenna tip at 400x:

Fly antenna tip at 400x.

Fly 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:

Fly front leg 100x.

Fly front leg 100x.

Middle leg:

Fly's middle leg. 100x magnification.

Fly’s middle leg. 100x magnification.

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

Fly middle leg's tip. 400x.

Fly middle leg’s tip. 400x.

Rear leg:

The tip of the rear leg is in air pocket while the rest is not. 100x magnification.

The tip of the rear leg is in air pocket while the rest is not. 100x magnification.

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:

Fly rear wing at 40x.

Fly rear wing at 40x.

Rear wing at 100x:

Fly rear wing at 100x. Click and zoom for more detail.

Fly rear wing at 100x. Click and zoom for more detail.

Rear wing at 400x (focus stacked):

Fly rear wing at 400x. Two images focus stacked.

Fly rear wing at 400x. Two images focus stacked.

Fly Eye

The eye came out remarkably well.

A fly's eye. 100x magnification.

A fly’s eye. 100x magnification.

Citing this post: Urbano, L., 2013. Insect Appendages: Practicing Mounting Specimens, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Ice and Snow on the Water

March 5, 2013

Ice and snow on partially cover the creek, but the rocky stream bed is still visible where the water is yet unfrozen.

The creek is a wonderful subject for photography as well as geology and ecology.

Citing this post: Urbano, L., 2013. Ice and Snow on the Water, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Rethinking Classrooms with Pedagogy in Mind

June 26, 2012

OnlineUniversities.com has compiled an interesting list of ways what we’ve learned from neuroscience is being used to rethink school and the classroom.

From 9 Signs That Neuroscience Has Entered the Classroom via OnlineUniversities.com.

Much of the list consists of simpler, practical things that are straightforward (if not easy) to implement: like starting school later (for the adolescents), emphasizing more group work, and stressing the importance of the emotion (positive affect).

But the article also points out some of the newer technology based approaches, such as interactive “cognitive tutoring”.

It’s a useful introductory reference.

K.Cole.

Citing this post: Urbano, L., 2012. Rethinking Classrooms with Pedagogy in Mind, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Radishes

April 29, 2012

Radishes ready for harvest.

The radishes did well this year. Planted in containers on March 29th (in St. Louis, USA), they were harvested one month later. The short, early season means that they’re a workable crop for school. Students can plant, harvest, and consume them all within a semester.

The CDC’s Fruit and Vegetable of the Month website has a little history, some information about the varieties, nutritional information, recipes, and more information about radishes. The University of Illinois Extension also has information about planting and growing.

NutritionData.self.com has some very nice graphical representations of the nutritional value of the food (although their serving size is 1 cup of slices, which seems a bit much).

These sites, however, focus on the radish bulbs, and not on the fact that the leaves are edible. Radish Leaf Pesto is quite good.

Harvested radishes. Both the red bulbs and the green leaves are edible. You'll note that radishes also spot a long tap-root.

Citing this post: Urbano, L., 2012. Radishes, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Coal in Their Stockings

December 25, 2011

I told my two (elementary aged) kids that if they didn’t behave Santa would fill their stockings with coal. They were so excited. Since the coals we use on the grill can’t melt metal, they were hoping some real coal would burn hotter. They want to make rings.

Citing this post: Urbano, L., 2011. Coal in Their Stockings, Retrieved May 30th, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

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