Thursday
August 28, 2008
(Class Discussion)
Bell Ringer
8-28-08
A science class is conducting an experiment that
produces noxious fumes. Because of inadequate
ventilation, some students begin to feel
nauseated and dizzy. The first response should be
to:
A. neutralize the acid that is reacting to produce
the noxious fumes.
B. carry the reactants outside, away from other
students.
C. leave the room and go to an area with fresh
air.
D. spray the reaction with a fire extinguisher.
Bell Ringer
8-28-08
A science class is conducting an
experiment that produces noxious
fumes. Because of inadequate
ventilation, some students begin to
feel nauseated and dizzy. The first
response should be to:
C. leave the room and go to an area
with fresh air.
Assignments
 The Science Class Information
Sheet is now two days overdue!
 The Class Procedures and
Expectations signed sheet is one
day overdue.
 The signed Flinn Scientific's
Student Safety Contract is due
today.
The Scientific Method
 How do scientists solve problems
and gain knowledge?
 They use a step-by-step procedure
called the “Scientific Method.”
 The Scientific Method is a plan that
is followed in performing a
scientific investigation and
analysing the results.
Steps in the Scientific Method

Make an observation about something that interests you.
• You have heard that taking one aspirin per day for 60
days decrease blood pressure in females ages 12-24?
•
State the problem by asking a question.
• Will taking one aspirin per day for 60 days decrease
blood pressure in females ages 12-24?
•
Formulate a hypothesis (an educated guess that is testable
using experimentation) that you believe answers the
question. A hypothesis should be written in the 1f-then
format.
• If a female aged 12-14 takes one aspirin per day for 60
days, then it will decrease her blood pressure.
•
Design and conduct an experiment to test your hypothesis.
• Test 100 females, ages 12-24, to see if taking one aspirin
per day for 60 days decreases blood pressure in those
females.
Steps in the Scientific Method

Collect and analyze the data. Study the
results. In most cases, organize the data into
tables and graphs.
• In this experiment, out of 100 females, ages 12-24,
76 had lower blood pressure readings after taking
one aspirin per day for 60 days.
•
Make a conclusion. What does the data
indicate? If the hypothesis correct?
• In this experiment, it appears that taking one
aspirin per day for 60 days decreases blood pressure
in 76% of females, ages 12-24,therefore the original
hypothesis has been verified – that aspirin does
have some effect in decreasing blood pressure.
•
Repeat the experiment many times! This is
why you must take careful notes on your
procedures and document everything
thoroughly. You (and others) must be able to
repeat the experiment the same way multiple
times!
Steps in the Scientific Method
 You must first divide your subjects into
two equally sized groups:
 50 individuals will go into the experimental
group, which is the group that will be
subjected to the experimental variable.
 The other 50 individuals go into the control
group, which is the group that does not
receive the experimental variable.
 An experiment should have only one
variable at the start of that experiment.
This is the experimental, or independent
variable. This is the variable that you
change, on purpose, in the experiment.
Steps in the Scientific Method
 All other factors in the experiment are
identical for both groups. There are
referred to as the constants.
• In this experiment, taking an aspirin or not
would be the independent variable. The
members of the experimental group would
all take the aspirin, while the members of
the control group would not take the
aspirin.
 The dependent variable is the response
to the independent variable.
• In this experiment, the blood pressure of the
individuals in the experiment, which may
change from taking aspirin.
Vocabulary
 A variable is a factor that affects
the result of an experiment, and
it varies, or changes.
 The independent variable is
what you change in the
experiment.
 The dependent variable changes
based upon how the
independent variable changes.