Search for Science Fair Projects

1000 Science Fair Projects with Complete Instructions

Attribution: This is a cached copy of a third party project. Many of these sites are from 20 years ago and the majority are no longer running. We show only the first page of the project. We do not save all pages since copyright belongs to the third-party author.

Although we can’t always see them, microorganisms are present in almost all
environments. Many can be grown in the laboratory on plates containing a solid,
nutrient-rich medium (agar plates). After several days, a single bacterial
cell grows into a population of bacterial cells that is visible to the naked
eye. This population of cells is called a microbial colony. In this exercise we
will test for the presence of microorganisms on our hands and on objects we are
in contact with.

- Sterile agar plates (1 per student)
- Objects of your choice to test for the presence of microorganisms: a penny,
keys, pens, etc.
- Q-tips (to get bacteria from teeth, sandwiches, fruit juice, etc.)
- Toothpicks


 1. Get an agar plate and label it on the bottom with your name and the date and
the objects that you are going to test for microorganisms. This agar plate is
sterile – it has been heated and no bacteria are on it. Try

dividing your plate into sections by drawing lines on the bottom of the plate
(on the outside) and trying different objects in each section.


2. Open the cover of the plate and gently press your object on the surface of
the agar. Be careful not to press too hard – you don’t want to press through the
agar. Make sure to label what object you used in each section. If you want to
try testing food, drinks, your teeth, etc., then wet the Q-tip with the object,
and then rub the Q-tip on the surface of the agar. You can also use a toothpick.

3. Cover the plate as soon as you remove your object or the Q-top or the
toothpick. You want to have the lid open for as little time as possible
so microorganisms from the air do not fall on the plate. Your plate will be left
at room temporate for a couple of days so any bacteria that are present can grow
into colonies. After colonies appear, the instructor will keep it at 4oC inthe
refrigerator until the next class.

1. Record what happened on your plate.

1.1. Sketch your plate. Label your drawing so that you know what objects
the colonies came from.

1.2. Record size, color, texture, and shape of colonies.


2. Prepare samples of the microorganisms on your plate by using the methyl blue
staining method.

2.1. Place a few drops of stain on the slide.

2.2. Use a toothpick to smear some of the bacteria from one colony on
the slide and mix it into the stain. You should take only enough bacteria to
cover the tip of a toothpick – definitely not more! If you take too many cells,
you won’t be able to see them clearly under the microscope.

2.3. Carefully place the cover slip over the bacteria.

3. For each sample, examine it under the microscope and draw the bacteria.
You will need to use the highest magnification on the microscope to see the
bacteria. Make sure you record which colony it came from. If you find a
well-stained sample, take it to the videomicroscope so that everyone can see it.

4. On your plate, you used many different objects to grow bacteria. Do some of
the bacterial colonies look similar? If so, why do you think this is?

 5. If some bacterial colonies look very different from one another, why do you
think this is?