Download The Scientific Method

Designing
A
Controlled Experiment

Some discoveries happen by chance but the
standard is for a scientist to begin with
forming a question.

The more limited the question, the easier it is
to set up an experiment to answer it.

Before you can write your hypothesis, you
need to identify the variables in your
question.
 Independent variable: The factor you want to
test. It is changed by the investigator to observe
how it affects the dependent variable.
 Dependent variable: The factor you measure or
observe during an experiment.
 Variable Worksheet

Take an educated guess, hypothesis, about
the answer to the problem or question.

A hypothesis uses your prior knowledge and
observations to predict what will happen and
why.



Identify independent and dependent
variables
Will one variable affect the other?
Write the hypothesis using the following
format:
 If the [independent variable] increases or
decreases, then the [dependent variable]
increases or decreases.
 Writing Hypothesis Worksheet



To test how the independent variable affects
the dependent variable, you need to keep all
other factors the same for each test.
Constants: The factors that remain the
same.
Without constants two independent variables
could change at the same time and you won’t
know which variable affected the dependent
variable.
 Three Kinds of Variables Worksheet

Qualitative Observations: Use your 5 senses
to describe what is happening.

Quantitative Observations: Use
measurements (numbers) to describe what is
happening.
 Confection Connection Worksheet
 Penny Observation Worksheet

Reporting of the data should state specifics of
how the measurements were calculated.

Graphing Data: Graphing takes numbers and
shows patterns that you might not notice.
 Graphing Packet

Describe trends you see in the data.

Compare the results to your hypothesis.

Use evidence in your results to support your
conclusion.
 The End
 Thinking Map