Name Period Date
Worksheet: Hypothesis or Theory?
Read the text below and answer the questions that follow.
As scientists make observations and carry out investigations, they generate,
analyze, and compare data. Their observations, analyses, and comparisons can
lead to the formation of hypotheses and theories. Both hypotheses and theories
are tools used by scientists, but they are very different from one another. How
can you distinguish one from the other?
Hypotheses are testable statements that must be able to be supported or not
supported by observational evidence. Scientist frequently write hypotheses
as “if…then” statements. A hypothesis usually serves as a basis for a single
experiment and, therefore, relates only to a limited amount of data. If a
hypothesis is supported by the data, it may be considered correct, but only for
that experiment. Many more experiments would have to be performed and much
more data collected in support of the hypothesis before the hypothesis can be
used to predict results of other experiments and explain observations.
Theories, on the other hand, are explanations that are based on vast amounts
of data accumulated over long periods of time. Theories usually incorporate
the observations, data, and explanations of many scientists. Theories are broad
generalizations that can explain a body of information and observations and can
accurately predict the results of many experiments. Although scientific theories
are occasionally modified as the result of new scientific information, they have
been repeatedly verified by many individuals, and are highly reliable explanations
for natural phenomena. New scientific theories are introduced only occasionally,
because they are based on such large amounts of information.
Complete each statement below, using the term hypothesis or theory.
1. A scientist observes that penguins move efficiently though water. The
scientist makes a ________________ that if a boat is designed with a
propulsion system that moves like a penguin, then the boat will be more
efficient than traditional boats.
2. Scientists have developed a ________________ to explain the characteristics
and behavior of light that is based on work performed by many scientists.
3. A student notices that sound travels quickly underwater. She develops a
________________ that sound will move more quickly through water than it
moves through air.
4. Scientists use a ________________ to interpret the results of investigations
about the structure and behavior of atoms.
