Posts of the Category: Labwork
This category contains posts with labwork that can be done in a school.
Dry-mounted permanent slides
Wings of insects, small insects and other small specimens do not have to be enclosed in a mounting-medium, they can also be dry-mounted. If they are completely dry, then they will also store for a long time.
Processing Specimens for Microscopy
Not all microscopic specimens can be observed directly with a compound microscope, many of them need to be brought into a form which is suitable for observation. Different specimens have to be processed differently. This article gives an overview of different preparation methods.
Observing a Kiwifruit
Soft specimens can be observed by squashing a small sample between the slide and the cover glass. Here I would like to present: a Kiwi fruit
Fructose Mounting Medium for Permanent Slides
Many mounting media for making permanent microscope slides include organic solvents and are less suitable for the use in classrooms, at home and with children. In this article I would like to show you how to make fructose syrup to be used as a safe mounting medium.
Observing Brownian Motion
Brownian motion is the random movement of particles. It is possible to observe this movement under the microscope.
Staining Yogurt Bacteria
School microscopes are often not equipped with phase contrast optics, which would be suitable for viewing bacteria. It is possible to see bacteria also in regular bright field, but the results are better if they are stained. Yogurt bacteria are safe for the use in schools.
Some Safety Issues
Here are some safety issues to consider when doing microscopy lab work. This is not a comprehensive list.
Observing Leaf Stomata
It is possible to observe the impression of leaf epidermis cells on white wood glue. The stomata and guard cells are easily visible. The regular shape of the stomata makes it an ideal specimen for practicing drawing.
Observing Plasmolysis
It is possible to observe the plasmolysis of cells under the microscope. When salt water is added to onion cells, then the cells will lose water due to osmosis, this can be observed.
Determine Cell Size with a Slide Projector
This is one of my favorite lab activities. Onion cells are visualized using a slide projector. Using an internal reference mark, the students can calculate the actual size of onion cells. It does not require the use of microscopic equipment and can be conducted in the normal classroom (lab not required).
Making a Hay Infusion
It is possible to enrich microorganisms such as ciliates by making a hay infusion.
Growing Paramecia
Paramecia are fresh-water ciliates that make excellent microscopic specimens. They are relatively large and therefore easily observable, even under low magnification. Pond water usually does not contain sufficiently high concentrations of them. For educational purposes it is necessary to enrich them.
Growing Crystals
Crystals of organic substances make interesting microscopic specimens to be viewed under polarized light.
Staining of Onion Cell Nuclei
This is a simple preparatory technique that allows students to observe the otherwise difficult to see nucleus of onion cells. There is no need to employ, possibly harmful, DNA staining chemicals.
Observing leaf veins
This is a simple but somewhat time-consuming preparatory technique. It is possible to isolate the vascular bundles of certain leaves and prepare them for microscopic observation. The prepared leaf veins make an ideal specimen for stereo microscopy. The microscope allows the students to perform a quality-check of their preparation.
