Transcript Notes, 9/12/07 - Saint Paul Public Schools

Scientific Method Notes,
9/9/14
Science is a Search for
KNOWLEDGE that is based on
EVIDENCE
Steps of a Scientific Method
1. Gather Information. Make Observations using your 5
senses.
2. Ask questions and define the problem.
Observations make us ask questions about what we
experience.
Science uses evidence to answer testable questions.
3. Make a Hypothesis
• Observations and questions lead to
possible solutions.
• A hypothesis is a possible explanation
that is based on observation and seeks
to answer the question.
• A valid hypothesis is in the form of an if,
then statement
3. Hypothesis
Ex: “If the gene for glowing is inserted into
a plant, then the plant will produce the
glowing trait.”
4. Test the hypothesis
(Experiment)
• A controlled test of a hypothesis is
called an experiment.
• A valid experiment has two variables
(things that change) and a control.
Variables
• Any valid experiment has only two
things that change - (The independent
variable and dependent variable)
• The independent variable is
manipulated. It is the thing in the
experiment that you directly change!
• The dependent variable changes in
response to the independent variable. It
is the thing that you measure!
Variables
Constant Variables
• Any valid experiment will only have two
variables that change. All other things
that could change MUST be kept the
same.
• Any unchanging variables are called
constants or constant variables.
The Control Group
• One test group (the control group) is
not exposed to the tested effect
(variable).
• Another test group is exposed to the
tested effect (variable).
• Keep a control group for comparison.
Control and Variable
• What happens when a fire fly gene (the
variable) is added to tobacco genes?
• This is the test plant.
Quick Write!
• Describe an experiment to test the
effectiveness of a fertilizer on tobacco
plant growth.
• Define the independent and dependent
variables, your control group, and three
constants.
5. Analyze Data
• The measurements and observations
made during the experiment are called
data.
• Data is evidence to support the
hypothesis. Data must be measurable
in someway.
• Data cannot be an opinion or emotion.
5. Data Cont’…
• Look at data for patterns and trends.
• Graphs and charts make patterns more
visible.
• Use the numerical data to
support your conclusions!
5. Data Cont’…
• 3 Types of Graphs
–Line graph is your data is
continuous (ie. Time)
–Bar if your data comes in
categories
–Circle if your data is part of a
whole (fractions or %’s)
5. Data Cont’…
• 3 Types of Graphs
–Line graph if your data is
continuous (ie. Time)
–Bar if your data comes in
categories
–Circle if your data is part of a
whole (fractions or %’s)
5. Data Cont’…
• Parts of a graph
–
–
–
–
Title (Effect of IV on DV)
Independent Variable (X-Axis)
Dependent Variable (Y-Axis)
Axes labeled with units
6. Form Conclusions
• Conclusions are only valid if data
supports it.
• Reject the hypothesis if the data does
not support the hypothesis.
Conclusions cont’...
• Error Analysis is part of conclusions.
• List only KNOWN errors in the
measurements
• DO NOT list your guesses (e.g. “We
might have....).
Theory
• When many hypotheses have
a large body of data and
support they are unified into a
Theory.