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How should I plan and perform my experiment?

Your experiment should be carefully planned and executed.  It should be designed to answer a specific question with only one variable.  You should keep a logbook which details every step taken.  For instance, if you water the plants, your logbook would have an entry which lists the day, time and amount of water given.  Data is carefully gathered at every step.  Observations are made and results are measured and recorded.

Begin by posing a question. Your experiment should have a definite purpose.   Lets discuss a simple experiment.  For instance, How does the temperature of the water affect the plant?  We would form and record our own opinion of what is likely to happen.  Then, we would research the subject to see if there is any information already available on the subject and revise our predictions if necessary.  At this point, we may choose to change the experiment based on our research, or continue with the original plan.

Plan an experiment with one variable and a control.  Lets continue with the original plan.  We would now plan an experiment which varies the temperature of the water used to water the plants.  We would want to use multiple plants at each temperature, perhaps 3-5, or as many as we could obtain.  Of course, all plants used would be the same type, of the same age and health.  Try to obtain plants that are as nearly identical as possible.  We would set up a watering schedule of different temperature water.  Perhaps we will use water at 32 degrees, 40 degrees, 50 degrees, 60 degrees, 70, 80, 90, 100 degrees, as high as we thought practical.  One set of plants will be watered with room temperature water.  This is our control.  We would probably expect the greatest effect on the very cold water and the very hot water.  It is important that we have enough time for the plants to grow and show changes that might be caused by the water temperature.  We would not expect to see changes overnight.


 It is very important that there is only one variable, so we would be sure that everything else is exactly the same.  The water temperature is our variable.  We would make sure that everything else was controlled carefully.  The plants would all be watered at the same time, with the same amount of water.  They would all receive the same amount of sunlight.   All plants get the same light, the same temperatures, etc.  We would record the details everytime we watered the plants, and we would record anything else that happens to the plants.  If one is accidently knocked off the shelf, we make a note of it in the logbook.  Everyday we would measure the growth of the plants and make a visual inspection, making a note in our logbook of all the details.  This data will be turned into a graph or chart later.

Keep a very careful record of everything in your logbook or journal.  It is better to write too much, than too little. Record the date, time, and everything that was done.  Record all of your measurements, observations and results.  You can also record your thoughts, observations, mistakes, and problems encountered along the way.   Your logbook or journal is a very important part of your science fair project.


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Last modified: 12/28/04