Name:
Scientific Investigation
Date:
Period:
Introduction
Science is the attempt of people to understand the objects and events they experience in
nature. People develop understanding about things they experience by asking questions
and finding answers. What is life? What causes animals to die? What happens to frogs in the
winter when their pond is frozen over? Why do so many different kinds of plants and
animals exist? In attempting to find answers to such questions as these, you are doing
science.
The pattern of scientific investigation consists of the following five steps:
1. Raising a causal question.
a. A causal question is a question about the cause of something. They are
generally “why” or “how” questions.
2. Brainstorming hypotheses
a. A hypothesis is a possible answer to a causal question.
3. Imagining experimental conditions and generating logical predictions
a. A prediction is the expected result of an experiment if a particular
hypothesis is true.
4. Gathering and analyzing data
5. Drawing conclusions
Part A.
Two exhausted parents want to know why their one-year-old keeps waking at 5 in the
morning. Consider each of the following statements. Label each according to the step of the
process of scientific investigation that it represents.
_________When the sunlight was blocked, the child slept much longer.
_________Why was the child waking up so early?
_________Perhaps the sunlight is awakening him.
_________If the sunlight is blocked by heavy drapes, the child will sleep later.
_________The sunlight caused the child to wake up.
Name:
Scientific Investigation
Date:
Period:
Part B.
An ecologist observes that gazelles leap into the air when the gazelles spot a cheetah.
Consider each of the following statements. Label each according to the step of the process
of scientific investigation that it represents.
__________If we observe gazelles with and without offspring, gazelles that have no offspring
in the herd should not leap into the air at the sight of a predator.
________Attracting a predator’s attention away from young is not the purpose of gazelles’
leaping into the air at the sight of a predator.
_________Why do gazelles leap into the air when they see predators?
_________Maybe gazelles leap into air when they see predators to draw attention away from
their more vulnerable offspring.
_________Gazelles with no offspring jump into the air at the sight of a predator just as often as
gazelles with offspring.
Part C.
Clever Hans was a very special horse. According to newspapers around the turn of
the century, he could do math. When his owner would ask him to add numbers, Hans would
tap out the answer with his hoof.
Understandably, many people were skeptical about this, so a group of “experts,”
including two zoologists, a psychologist, a horse trainer, and a circus manager, were
brought in to investigate. They watched closely as Hans’ owner asked question after
question to which Hans replied with near-perfect accuracy. Hans was even able to reply
correctly to questions posed by perfect strangers. The experts were unable to discover any
tricks and thus were forced to conclude that Han was a very clever horse indeed.
After reading the reports, a young psychologist proposed a different explanation.
Suppose Hans was not able to think out the answers at all. Suppose instead he was able to
monitor subtle changes in the questioner’s facial expression, posture, and breathing that
would occur when Hans arrived at the correct answer. Perhaps these cues told Hans when
to stop tapping.
How could this explanation be tested? The psychologist decided he needed to have
some questioners who did not know the correct answers. If the questioner did not know
the correct answers, then his or her expressions could not cue Hans, and Hans’ success rate
Name:
Scientific Investigation
Date:
Period:
should drop considerably. Sure enough, when the interrogator knew the answer, Hans
succeeded on 9 out of 10 problems. When the interrogator did not know the answer, Han’s
score dropped to just 1 out of 10. Hans did not know math; he just knew how to read people.
What is the young psychologist’s causal question? (This should be in the form of a
question.)
What is the young psychologist’s hypothesis? (This should start with a word like “maybe.”)
What is the young psychologist’s imagined experiment and prediction? (This should be in
the form of an if-then statement. See Cases 1 and 2 for a model).
What are the results of the young psychologist’s experiment?
What is the young psychologist’s conclusion?
* Check your answer with Dr. Moore now*
Name:
Scientific Investigation
Date:
Period:
Part D.
Imagine you take a walk in a park and see two trees. One tree has thick grass at its base and
the other tree has bare soil at its roots.
What causal question is raised?
Generate 3 alternative hypotheses to answer this question.
1.
2.
3.
Describe an experiment to test one of your hypotheses.
State an expected result based on the assumed truth of this hypothesis and your
experimental design.
Name:
Scientific Investigation
Date:
Period:
Part E.
Homing pigeons are domestic pigeons that have been bred to find their ways home over
extremely long distances. Classify sentences 1 – 8 into one of the following sentence types.
a.
b.
c.
d.
e.
f.
g.
h.
Causal question
Noncausal question
Hypothesis
Experiment
Prediction
Experimental result
Irrelevant fact
Conclusion
1. _________ Most homing pigeons are gray.
2. _________ Frosted contact lenses were placed over the eyes of a number of pigeons.
3. _________ Many of the pigeons wearing frosted contact lenses were able to find their
way home.
4. __________ Homing pigeons do not use sight to find their way home
5. ________ Perhaps homing pigeons use sight to recognize landmarks and get back
home.
6. _________ How do homing pigeons manage to find their way home?
7. _________ How long did it take the pigeons to return?
8. _________ If homing pigeons use sight to find their way home, then pigeons whose
sight is obscured by frosted contact lenses should not make it home.
Name:
Scientific Investigation
Date:
Period:
Part F. Each of the cards has a letter on one side and number on the other. Your friend tells
you that every card that has a vowel on one side has an even number on the other side.
Which cards must be turned over to allow the rule to be tested? Explain.
E
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