Elodea plants are water plants that are often called water weeds. They are native to North America and are a common addition to aquariums because of their attractive appearance. Elodea plants boast white flowers that grow at the water surface. The leaves are only two cells thick, so you can observe them under a microscope. Their cellular walls are semipermeable membranes, so solvents pass through easily. By looking at them under magnification, you can observe osmosis.
Put a drop of water on the center of the slide. Grab an elodea leaf with forceps and place it in the water.
Pick up a cover slip with tweezers or forceps. Place the slip on top of the leaf, carefully covering it. This will flatten the specimen. If there are air bubbles under the cover, try to push them out by running the forceps over the cover. You can also remove the cover and put it in place a second time.
Set the slide on the microscope stage. Look at it at 40x and 100x. Write down what you observe, including shape, size and color details. Note the cell patterns you observe.
Remove the elodea slide from the stage. Drop 5 percent salt solution to the left of the cover slip. Use the dropper to release 2 to 5 drops. Keep the slide level.
Lay a paper towel to the right of the cover slip. It should absorb the tap water from under the slip, drawing the salt water in from the left side. You're essentially replacing one liquid with the other.
Replace the slide on the microscope stage. Look at it using 40x and 100x magnification. Write down your observations.
Use a paper towel to remove the 5 percent salt solution. Add 2 to 5 drops of the 10 percent salt solution. Observe the elodea leaf again, using 40x and 100x. Record what you see, including the changes that occur with different solutions.