Archive | November 2012

Looking at leaf stomata

Over time I’m going to write more and more about the short practicals that I tried out in school. I’m sure not many of these will be original or even properly work but like always I like to share what I’ve tried and archive it so I can find it later. So to start with we have my first biology practical. This is looking at the stomata in leaves. This is a nice short practical that doesn’t require many resources.  I’ll put the instructions below but we got some really nice results in the class and one of my favourites can be seen below (or the one I got to before we had chucked all the slides away).

Looking at Stomata

Materials: Plant leaves, Clear fingernail polish, Clear cellophane tape (clear package sealing tape), Microscope, Microscope slides

Make the slide:

1. Obtain a leaf from a plant

2. Paint a thick patch of clear nail polish on the leaf surface being studied. Make a patch at least one square centimetre.

3. Allow the nail polish to dry completely.

4. Tape a piece of clear tape to the dried nail polish patch. (The tape must be clear)

5. Gently peel the nail polish patch from the leaf by pulling on a corner of the tape and peeling the fingernail polish off the leaf.  This is the leaf impression you will examine.

6. Tape your peeled impression to a very clean microscope slide.

Looking at slide:

Scan the slide until you can see the stomata. Each stoma is bordered by two sausage (or donut?)-shaped cells that are usually smaller than surrounding epidermal cells. These small cells are called guard cells and contain chloroplasts.

A graphical tool for demonstrating the techniques of radio interferometry

I’ve previously written about the tool that Adam Avison and I came up with for the ALMA stand at the Royal Society Summer Science Exhibition. We are now pleased to be able to tell you about the paper we have written up about this. The paper explains the basics of interferometry and how one can use our tool to help teach this topic. The paper is mostly aimed at undergraduate level but the tool can be used with all ages. It can be used to nicely demonstrate what having a bigger aperture means and how radio astronomy need very large dishes (or large arrays) to produce useful images.

The paper published in the Publication in the European Journal of Physics can be found on arxiv here.

ALMA Summer Science Exhibition Mosaic