ConsumerFairExperimentalDesignguidelines by gegeshandong


      After you have chosen a topic, look for two things that are related in a
particular topic area and ask a question about the relationship. You should be able
to conduct a test (experiment) to find the answer to the question you ask. There
should be a cause and effect relationship between the two things you are studying.
The question should point out the cause and effect relationship and will be the
purpose of your experiment.

Here is a sample chart of topics, topic relationships, and questions.

Topics             Topic Relationships          Questions
Plants             plants and fertilizers       Which plant fertilizer, Miracle-Gro or
                                                Giant Magic Grow, causes petunias to
                                                grow taller?
Temperature        temperature and              Can insulation cause an ice cube to
                   insulation                   melt at a slower rate?
Detergent          dishwasher detergent         Does Cascade Complete really remove
                   and food on dishes           food particles from dishes without
                                                pre-washing or pre-rinsing?
Paper Towels       brand and absorbency         Do Bounty paper towels soak up more
                                                liquid than Scott paper towels?

       The problem is the scientific question to be solved. It is best expressed as
an "open-ended" question, which is a question that is answered with a statement,
not just a yes or a no. Ideally, it is written in a form beginning, “What is the
effect of ______ on ________?” For example “What is the effect of Cascade
Complete on the removal of food particles from dishes without pre-washing or pre-

Limit your problem. You want to conduct an experiment about one aspect of your

      Choose a problem that can be solved experimentally. For example, the
question "How does dishwasher detergent work?" can be answered by finding the
information online or in a book on dishwashers. But “Does Cascade Complete really

removes food particles from dishes without pre-washing or pre-rinsing?” is a
question that can be answered by experimentation.

Remember . . .
Your problem should be written in the form of a question. The question should
show a cause and effect. In fact, try to word the question so that it starts “What
is the effect of _____________ on ________?
                                         The cause is something that can be
                changed or manipulated. It is also called the independent variable.
                                         The effect is the result of the cause. It
                is also called the dependent variable.

Identify the Variables

      Remember the cause is the independent variable. This is the variable you
are testing, manipulating, or changing.

      The effect is the dependent variable. This is the variable you are
measuring. It depends on what the independent variable does. In the case of a
consumer product experiment, the independent variable is often the brands of the
product you are using. The dependent variable is what happens when different
brands of product are used in a particular way.

Besides the independent and dependent variables, there are two other types of
variables associated with science fair projects. These are the control and the
constant variables. Sometimes you will see these variables referred to as
controlled variables, without differentiating between them.

       The constant variables are those things that you must keep the same, so
that the experiment will be a fair test. If an experiment were set up to test if
Miracle-Gro plant fertilizer really did cause petunias to grow taller, then the
variables such as pot size, amounts of sunlight, and amounts of water must remain
constant. If only the independent variable, which in this case is the two brands of
fertilizer, is changing, then it will be a fair test of that variable’s effects.

       The control is the absence of the independent variable. In the case of the
petunias, at least one plant would have to be grown without fertilizer (water only)
to compare it to the growth of plants that had been fertilized. In the case of the
insulation, an ice cube would have to be tested to see how fast it would melt when
no insulation was used. The results would be compared with the melting speed of
an insulated ice cube. In the case of the dishwasher detergent, dishes would have
to be washed with water only to compare them with dishes washed with the

       In an experiment comparing two products, it is not always possible to have a
control. If you are comparing a store brand with a national brand, you might
choose either brand to be your control. Since you can make this choice, neither
one is really a control in the sense of the definition above. This is the situation if
you are comparing two brands of batteries to see which one lasts longer or if you
are studying two brands of paper towels to see which one absorbs more liquid. If
this is your situation, just write “This is a comparison, there is no control.”

Write Your Hypothesis

       A hypothesis is an educated prediction of what you think will be the answer
to the problem you are studying. It is educated because it is based on research
you have done. It is just a guess so you may guess or predict incorrectly and your
hypothesis may be proven incorrect. That is why you did the experiment in the
first place – to find out what will happen.

       The hypothesis is a restatement of the problem (which is in question form)
in a special sentence form. The form for the hypothesis is “If ______________,
then ______________ because ___________________.” If something is done
with my product brands, then this will happen because the research said this and

      When writing a hypothesis look for a cause and effect relationship in your
      Remember the cause is the independent variable. This is the variable you
are testing, manipulating, or changing.

     The effect is the dependent variable. This is the variable you are


       1. Dishwasher detergent
       Problem: Does Cascade Complete really remove food particles from dishes
without pre-washing or pre-rinsing, compared to other types of Cascade
detergents? Or, What is the effect of various kinds of dishwasher detergents on
the removal of food particles from dishes without pre-washing or pre-rinsing?
       Research: Cascade Complete’s formula dissolves tough food particles so
they don’t get stuck on other dishes or trapped in the dishwasher. Particles that
are not pre-rinsed will be dissolved by the detergent and the dishes will not have
any food residue remaining on them
       IV: various kinds of dishwasher detergent.
       DV: amount of food left on the dishes.
       Hypothesis: If dirty dishes are not rinsed before washing and are washed
using Cascade Complete or Cascade dishwasher detergent, then the dishes washed
with Cascade Complete will have no food residue remaining on the washed dishes
because Cascade Complete’s formula dissolves food particles so they don’t get
stuck on other dishes or trapped in the dishwasher.

      2. Plant fertilizer
      Problem: Will Miracle-Gro or Giant Magic Grow plant fertilizer cause
petunias to grow taller? Or, What is the effect of various kinds of plant fertilizers
on the growth of petunias?
      Research: Plants need potassium (K) to grow. Miracle-Gro contains 4 mg of
K and Magic Grow plant fertilizer contains 2 mg of K.
      IV: brands of fertilizer
      DV: growth of petunias (height)

       Hypothesis: If Miracle-Gro and Magic Grow plant fertilizers are used on
petunias, then the petunias will grow taller with Miracle-Gro because Miracle-Gro
fertilizer contains more K, an essential nutrient that helps petunias grow.

      3. Insulation

       Problem: Can insulation cause an ice cube to melt at a slower rate? Or,
       What is the effect of various types of insulation on the rate ice cubes melt?
       Research: Insulation like Styrofoam keeps the temperature inside the
insulation constant. It keeps heat out and cold in or cold out and heat in.
Styrofoam is a better insulator than wool.
       IV: type of insulation
       DV: amount of time it takes for an ice cube to melt

       Hypothesis: If ice cubes are place in containers with Styrofoam or wool
insulation, then the ice cubes in the container with the Styrofoam insulation will
take longer to melt than the ice cubes in the container with the wool insulation
because Styrofoam keeps the temperature inside insulated containers constant.

Design the Experiment

       To determine if your hypothesis is correct, you need to conduct a simple
experiment. The step-by-step directions for this experiment are called the
procedure. The procedure is like a recipe. You need to tell times, sizes, amounts,
and in what order each step is to be done. The directions should be clear enough
that another person will be able to do your experiment exactly the same way as you
did it. It helps to have someone read the steps out loud to you as you listen to
them. You may be able to catch something that needs to be added or explained
more clearly.

        Write out your experimental procedure as a numbered list of directions. If
it is necessary to revise your procedure as your experiment is conducted, discuss
the revisions and the reasons they became necessary in the Observations and Data
section of the report. The Procedure section of your report should include the
final procedure you followed in the experiment. If you originally planned to follow
a different procedure, you should indicate where the procedural changes, if any,
were made, at the end of the Procedure section. Discuss the reasons you made the
changes in your Observations and Data Section of the report. Remember that if
you make any changes to your procedure, then you must restart the experiment
completely, following the revised procedure. In the Data Analysis section, you
should discuss the differences between the results obtained using the first
procedure and the revised procedure.

      Be sure to use enough test samples in your experiment and repeat the
experiment at least three times. This is important to help make sure that your
results are repeatable and accurate.

      Use metric measurements in your procedure. A chart showing conversion
factors for most of the standard measurements you might be using is found on the
next page.

        After writing the procedure as a numbered list of directions, put together a
list of materials and supplies you will need to conduct the experiment. Keep track
of the cost of the various materials you need to purchase so that you can calculate
the cost of using your product. If you are testing more than one brand, keep track
of the cost of each brand.

       After writing your procedure and list of materials, check them over. Make
sure that the independent, dependent, control, and constant variables have been
accounted for in the procedure. Make sure all the materials and supplies have been
listed. Finally, check that you are using metric measurements.

      Make as many data recording sheets as you need to record the data from
your experiment. Use a table (a diagram that uses words and numbers in columns
and rows to represent data) to record data. Make sure it is clearly labeled.

                                                Metric Measures Up
                                        METRIC CONVERSION CARD
 Approximate Conversions to Metric Measures
Symbol       When you know              Multiply by                         To find                           Symbol

in              inches                                     2.5              Centimeters                       cm
ft              feet                                       30.0             Centimeters                       cm
yd              yards                                      0.9              Meters                            m
mi              miles                                       1.6             Kilometers                        km

in2             square inches                              6.5              Square centimeters                cm2
ft2             square feet                                0.09             Square meters                     m2
yd2             square yards                               0.8              Square meters                     m2
mi2             square miles                               2.6              Square kilometers                 km2
                acres                                      0.4              Hectares                          ha
oz              ounces                                      28              Grams                             g
lb              pounds                                     0.45             Kilograms                         kg
                short tons (2000 lb)                       0.9              Metric ton                        t

tsp             teaspoons                                    5              Milliliters                       mL
Tbsp            tablespoons                                 15              Milliliters                       mL
in3             cubic inches                                16              Milliliters                       mL
fl oz           fluid ounces                                30              Milliliters                       mL
c               cups                                       0.24             Liters                            L
pt              pints                                      0.47             Liters                            L
qt              quarts                                     0.95             Liters                            L
gal             gallons                                    3.8              Liters                            L
ft3             cubic feet                                 0.03             Cubic meters                      m3
yd3             cubic yards                                0.76             Cubic meters                      m3

F              degrees Fahrenheit                   subtract 32,           Degrees Celsius                   C
                                                    multiply by 5/9
NIST United States Department of Commerce, Technology Administration National Institute of Standards and Technology,
Metric Program, Gaithersburg, MD 20899


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