Name:
Please use a color besides BLACK
when entering any text into this
document.
Save this file as
Your_Name_scientific_method.doc
and email it to me in an
attachment when you are
finished.
Scientific Method
The scientific method has five basic steps. We follow these steps in order to ensure that
we can form a solid conclusion about our problem. The scientific method is SIMPL
State a problem, Investigate, Make a hypothesis, Perform the experiment, and make a
Logical conclusion.
1. Stating a problem - something is considered a problem if its solution is not obvious.
Some crucial information is missing. Solving the problem involves finding this
missing information.
2. Investigate the problem-- the more you know about the problem the more precisely
you can state the problem and the less time you will waste looking for solutions.
3. Making a hypothesis a. Use what you know about the problem to predict a solution and try it.
b. Look for patterns that will help you make predictions about the problem.
c. Make a model, or a representation, of what you’re working with.
d. Break the problem down into smaller, simpler problems.
4. Performing an experiment - design an experiment that will provide a means for you
to make a solid conclusion on your hypothesis
5. Make a logical conclusion - a solid conclusion is related to the hypothesis and based
on the results of a well designed experiment.
List the five steps of the scientific method.
1.
2.
3.
4.
5.
EXPERIMENTAL DESIGN CONCEPTS
A science experiment is designed so that only one variable is being tested at a time. A
variable is something that is changed to study how this change affects the time being
studied. By changing only one variable, when you make your conclusion you can be
assured that it is only that one variable that is causing the effect.
1. Independent variable (IV) - the variable that is purposely changed by the
experimenter.
2. Dependent variable (DV) - the variable that responds and is the variable measured.
3. Constant (C’s) - all factors that are kept the same during the experiment.
4. Treatments (Trt) – The different ways the independent variable is changed.
5. Repeated trials (#Trs) - the number of objects/organisms undergoing treatment for
each value of the independent variable, or the number of times the experiment is
repeated.
To ensure we are performing a defensible experiment we place the above concepts into
an experimental design box. This box keeps all our information at hand so we can easily
view and make conclusions about our data. For example, see the below experiment.
Scenario: The rate of a metal reaction is affected by the concentration of acid.
Description: Susan found that magnesium reacts with hydrochloric acid. She wondered
if changing the concentration (strength) of the acid would affect how fast the reaction
occurred. Susan prepared five concentrations of hydrochloric acid, .25M, .5M, 1M, 2M,
4M. She placed a piece of magnesium in each concentration and described the intensity
of the reaction as fast, moderate, or slow. She recorded color changes in the metal as the
reaction occurred. She repeated the procedures four times for each concentration of acid.
The key to filling in the EDB is being able to recognize the concepts in the
given scenarios. Let’s look at another experiment. Underline the problem, color the
IV Blue and DV Green, italicize any constants, and write your own hypothesis. Fill in
the EDB as you go along.
Scenario: What kinds of metals give the most voltage in a battery?
Description: Tyler was studying batteries. He discovered that a battery works as
electrons flow between two dissimilar metals through a solution. He wanted to find out
what common metal combinations would give him the highest voltage measurements.
He decided to test copper-iron, copper-aluminum, copper-zinc, iron-aluminum, and ironzinc. He cut out strips of various sizes of the metals. Tyler prepared multiple salt
solutions. He placed each pair of metals into 50 mL of the solutions and measured the
voltage produced, using a voltmeter. Tyler conducted three with each pair of metals.
Problem:
Possible Hypothesis:
IV:
units:
Trt:
# trs:
123Ave:
DV :
C's:
Try one more on the next page-
units:
Scenario: The effect of salt on the freezing point of water.
Description: Amy was performing a special project in chemistry dealing with salt and
the freezing point of water. Amy prepared .5%, 2.5%, 6% and 10% salt solutions. She
put some ice in a Styrofoam container. She placed a test tube of each solution one at time
into the ice and began to make it freeze by turning it around and around in the ice. When
the solution in the tube turned to slush Amy took the temperature with a thermometer.
Problem:
Possible Hypothesis:
IV:
units:
Trt:
# trs:
123Ave:
DV :
units:
C's:
The experimental design box coupled with strict following of the scientific method will
ensure that you have a solid experimental design, and will provide you with everything
that you need to formulate a defensible conclusion.
Your turnLet’s see how you can do on your own. On the next page create an experiment
design to determine which of the following liquids has the greatest effect on plant
growth: Mt. Dew, Coca Cola, or water. Be sure to include in your box all the key
terms and their corresponding matches, as well as your hypothesis. There is no need
to actually perform this experiment, only practice with the EDB, and the scientific
method.
Fill in your experimental design box in the space belowProblem:
Possible Hypothesis:
IV:
units:
Trt:
# trs:
123Ave:
DV :
C's:
Give a brief explanation of your experiment below-
units: