Need to perform a science project for school? Why not see what types of things grow in pond water when it is kept at different temperatures. Find a local pond or stream and gather some water. Use a depression slide and cover slip to view the water through a high power microscope immediately after you collect it and draw some images (or capture the images if you have a digital microscope).
Now split your pond water into two separate sealed containers, such as washed out yogurt containers with lids. Place one of the containers in a warm sunny area. Put the other container in a ziplock bag (to keep your fridge clean!) and place it in the refrigerator.
After 1-2 days take a sample from each container and compare the specimens. Are there more living organisms in the warm or cold pond water? Do you notice any new specimens swimming in the pond water samples? Why do you think this is?
The image above is bacteria captured at 400x magnification. This is an example of something you might find in the pond water during your science project experiment.