Tag: microscope

Guide to Using a Microscope

Sitting innocuously on the clearance table at a Barnes & Noble (in Cedar Rapid, Iowa actually) was a copy of Georg Stehli’s The Microscope and How to Use It.

At 75% off it was less than $3, which is quite a steal for a guide to what I found to be the most fascinating piece of scientific equipment for my middle schoolers. One of their first natural world lessons was on how to use the microscope. In the classroom there was always one sitting on the shelf, protected by its translucent plastic cover, but easily accessible.

I also took one everywhere, including to the cabins on our immersion trips, which is where they discovered the crystalline structure of salt and sugar grains, and the microfossils at Coon Creek.

And, interestingly enough, my microscopy posts are some of the most popular posts on this blog (the onion cell is regularly in the top ten).

The Microscope and how to use it by Georg Stehli.

Apart from the basics of how to use a microscope, Stehli’s book goes into simple sample preparations and preservation for almost everything you’re likely to encounter in the curriculum, in the classroom, and in the back yard. Though neither crystal structure nor microfossils are covered, the techniques for looking a the hard parts of biological specimens are applicable.

I would have loved to have had a copy of this last year when I was trying to figure out which were the best dyes to use for some of the odder samples my students came up with, and how to make them into permanent slides. It’s not easy to find this kind of broad reference online.

Microscope photography!!!

Algae and amoebas at 400 times magnification.

Did you know that if you hold up a regular digital camera up to the eyepiece of a microscope you can take a great picture of a magnified slide! I didn’t. And I really didn’t think it would work when I tried it, but the results are remarkable. With a somewhat steady hand you can also make decent animations.

If you look carefully you can see the amoebas zipping around. I also have a really cool larger version too, which shows the entire slide..

I’ve never been very good at identifying things (I’m a lumper not a splitter) so all I think I can say for sure is that there are algae and protozoans in the picture. BiologyCorner has a nice identification guide for organisms usually found in ponds, which is part of one of their lessons, Biodiversity of Ponds.

Baking bread; the yeast question

Although I’m pretty sure I’d explained this before, I had a student ask me today what makes the bread rise. He’d been combining the ingredients to make bread for the student run business with a rather thoughtful look on his face. So I told him that yeast is a fungus that “eats” the sugar in the honey and “releases” carbon dioxide bubbles, which get trapped in the dough causing the bread to rise.

I could see the look of disgust racing across his face at the mention of fungi, so I asked, “Would you like to look at it?” He did, and he was not the only one. So after lunch I broke out the microscope, which we have not used much this year since we’re doing the physical sciences this year. A slide, a cover slip, a drop of the residue from the glass jar we used to mix the liquids for the bread, a quick (so very quick) demonstration of how to use the microscope and whallah.

Under 10 times magnification you could see hundreds of cells moving across the field of view. The students were impressed by how many there were. Under 40 times magnification you begin to see cell structures.

Image from Wikimedia Commons, but yeast under the 40x microscope objective looks pretty similar.

We’ll look at yeast again next year when we’re focusing on the life sciences, but when I think of the Montessori axioms that the role of the teacher is to prepare the environment and to follow the child, I think of situations like this. At this time, in this place, after kneading dough for half a year, the student asked the question, and everything was ready for him to answer the that question and whet his appetite for more.