The word ‘cell’ was coined by the English scientist, Robert Hooke, when he looked at a piece of cork under a microscope and saw the room-like partitions inside. Viewing a cork sample through the lens of your compound light microscope would be an interesting student activity to be able to understand cells better. Cork comes from the bark of an evergreen oak tree that grows only in the Mediterranean area. Sheets of the oak bark is taken from the tree, seasoned and boiled to become cork, which is especially useful as stopper to bottles and the like. With this simple microscope activity, the student or child can see the pores in the cork called lenticels and which way they are pointing. To start with, the student would need a cork from a bottle (cork can also be bought in bookstores and chemistry shops), a box cutter, an eyedropper, water, a blank microscope slide, a slide cover, a pair of tweezers, some tissue paper and petroleum jelly.

First, cut very thin slices from the cork that you have using your box cutter. Ask an adult to help you with this. Looking at thicker objects under the student microscope would result to a blurred image, since the compound light microscope allows only a two-dimensional view of the sample mounted on the microscope slide. Because of this, you have to cut the cork as thinly as you can to be able to see it better under the microscope lens.

Next, prepare a wet mount of your cork sample. Wet mounts are used so that there would be no extra refractions of the light coming from the microscope lamp, making the image being viewed clearer. To prepare a wet mount of your cork sample, place a drop of water on your blank microscope slide using an eyedropper. Then place the cork sample in the drop of water using the tweezers. Cover this gently with the slide cover, making sure that there will be no air bubbles trapped inside. If the water dries up while you’re still looking at it, see which side of the slide cover looks like it’s still wet and put some more water from that side using the eyedropper. You can also preserve the wet mount for a longer period of time by spreading a thin film of petroleum jelly around the slide cover. This is so you can observe your cork sample for the length of a few days without having to do another wet mount.

Now that you have your sample, you can look at the cork under the compound light microscope starting with a low power-objective. Do you see the small pockets of air in the cork that are surrounded by thin walls? Those are what Robert Hooke saw that reminded him of the cells in a monastery, which led to him calling those pockets cells. There is only air inside those pockets because all the living matter from the bark where cork is made from has already died.

Because there is only air inside, the cork stays buoyant over water or any other liquid. If used as a stopper for bottles, cork is cut at a slant that would keep the wine from leaking out through the holes inside.If you want to see living cells, looking at an onion sample under the compound microscope would be an interesting activity as well.