SKILL: WRITING HYPOTHESES
How Do You Write
a Hypothesis?
A scientific experiment is sometimes set up in order to test a
hypothesis. A hypothesis is a tentative explanation for something
that has been observed. It is sometimes stated as a general rule
or pattern. A prediction describes what will happen in a specific
experiment if the hypothesis is correct.
Analyzing an Experiment
You can write a prediction and hypothesis as an “If . . . , then . . . ,
because . . .” statement. “If” and “then” state the test and prediction, and “because” states the hypothesis.
For example, Jai tested the claim that all objects fall at the
same rate by dropping different objects from the top of a ladder.
He wrote an “If . . . , then . . . , because . . .” statement.
If I drop several objects at exactly the same time, then
they will all hit the ground with a single thump, because
objects fall at the same rate.
The following questions may help you write the statement:
a. If: What will you do or change in the test? What is the
independent variable and how will you vary it? Your
answer should follow the If.
b. Then: What result do you expect if the hypothesis is
correct? What is the dependent variable and how will it
change? Your answer should follow the then.
c. Because: What is the general idea or principle you are
testing? Your answer should follow the because.
Write a Hypothesis
Darren experimented with dropping objects into flour to make craters.
His hypothesis was that weight determines crater size. He tested his
hypothesis by dropping two balls of the same size but different
weights. He predicted that the heavier ball would produce a crater
of greater diameter. Write an “If . . . , then . . . , because . . .”
statement with Darren’s test, prediction, and hypothesis.
CHALLENGE Lara decides to test a claim that distilled water forms
spikes as it freezes. She fills half the compartments of an ice-cube
tray with distilled water and half with tap water. She puts the tray
in the freezer and will later examine the results. Write an “If . . . ,
then . . . , because . . .” statement for Lara’s experiment.
Chapter 1: The Nature of Science 31