Science Fair Guidelines
HYPOTHESIS
Cause & Effect Question:
This is the topic of your science fair project. It is the question you are trying to answer
by performing your experiment. It should be in the form “How does X affect Y?.” For
example, “How does soil type affect plant growth?”, “How does the brand of battery
affect the playing time of a CD player?”, “How does the temperature of a magnet affect
its strength?”.
Statement of Purpose:
This is a short statement (one paragraph) that discusses your reasons for choosing this
project. It explains what you hope to learn or expect to discover by investigating your
chosen topic. It is NOT a hypothesis – it should not say what you think the outcome will
be. It is focused on why you are interested and what type of information you think you
will learn.
Hypothesis:
A hypothesis is an educated guess about the outcome of an experiment. It is what you
believe the answer to your question will be, based on what you know so far. It should
be stated as an “If ______, then ______” statement”
For Example:
Question – How does soil type affect plant growth?
Hypothesis – If soil has more nutrients in it, then it will result in larger plants.
Question – How does temperature affect magnet strength?
Hypothesis – If the temperature of a magnet increases, then the magnet’s strength will
decrease.
Support for Hypothesis:
This section should be one or two paragraphs that discuss the reasons why you believe
the hypothesis to be true. You should talk about information you learned while
completing your research paper to document that the hypothesis is truly and educated
guess and not just a guess.
Variables:
Variables are all the things that have the potential to change during an experiment and
affect the outcome. The first step is to identify all the things that could influence your
experiment. You must then identify one as the independent or manipulated variable,
one as the dependent or responding variable, and the rest as controlled
variables/constants.
Independent Variable: Identify the independent variable. The independent variable is
the thing you are testing. It is the thing you are changing on purpose to see how it
affects the outcome. In the question “How does X affect Y?”, the independent variable
is X.
Dependent Variable: Identify the dependent variable. The dependent variable is the
thing that is affected or changed by the independent variable in the experiment. It is the
thing that you are observing. In the question “How does X affect Y?”, the dependent
variable is Y.
You should be specific about how you will measure this. For example: plant growth will
be measured by the height of the plant as opposed to the number of leaves or the
fullness of the plant, etc.
Controlled Variables: Identify other variables that need to be controlled. The
independent variable is changed on purpose. The dependent variables change as a
result of any change to the independent variable. You must ensure that every other
variable remains exactly the same throughout your experiment, so that the only thing
that affects your results is the independent variable.
For Example:
How does soil type affect plant growth?
Independent variable = soil type
Dependent variable = height of plant
Controlled variables = type and age of plants, sunlight, amount of water, amount of soil,
temperature, time of watering, amount and type of food
How does the temperature of a magnet affect its strength?
Independent variable = temperature of a magnet
Dependent variable = strength of the magnet – measured by the number of paperclips
able to be picked up at once
Controlled variables = size and type of magnet, size and type of paperclips, method of
touching the magnet to the paperclips
Guidelines:
 The section should be typed in accordance with the guidelines set forth in the middle
school handbook.
 The information should be arranged in the same format as it is presented on this
page, including headings.