Lesson 1
Designing Experiments Using
the
Scientific Method
Key Words
Scientific Method
Hypothesis
Experiment
Data
Conclusion
Procedure
Variable
Independent Variable
Dependent Variable
Control Group
Experimental Group
Trial
Experimental Error
Bias
Notice the color of our key words.
process
steps
problem
organized
answers
question
educated
guess
information
Identify the problem
Form a Hypothesis
Create an Experiment
Perform an Experiment
Analyze the Data
Modify the Experiment
Conclusion
Let’s use some of our “key words” in an investigation.
I want to know if warmer temps. cause robin eggs to hatch faster?
First, our procedure. (Step by step plan)
Variable
Number of eggs
Temperature
Humidity
Lighting
Control Group
4
85 degrees
70%
Low Light
Experimental Group
4
97 degrees
70%
Low Light
Variable- Factor that affects results of an experiment.
There are 2 kinds of variables.
*Independent Variable-Factor I change to find out what will happen.
Temperature
*Dependent Variable- Variable affected by changes in independent variable.
How long it takes the eggs to hatch
Control Group-Group used for comparison. All variables controlled by me.
Experimental Group-Group exposed to changes in independent variable.
Can you see what I changed in this group?
Every time we repeat this experiment it is called a Trial.
Do cows cause global warming?
Why was my number different than yours!?
• Maybe it was experimental error? Human Error
True value of measurement vs. Measured value
Sunflower Seed
6 mm
l___________l
You measured 6mm.
7mm
l___________l
Your lab partner measured
the same seed at 7mm.
Actual measurement was 6.5 mm. Why?
But I want my hypothesis to be right!
This kind of thinking can cause Bias.
Bias is a wish or expectation that your experiment will
lead to a certain conclusion.
Let’s watch a clip to better understand Bias.
scientists
observations
experiments
hypotheses
conclusions
results
The Bikini Bottom gang loves
science class and wants to do a
little research. Read the
description for each
experiment and use your
knowledge of the scientific
method to answer the following
questions.
Flower Power
SpongeBob loves to garden and wants to grow lots of
pink flowers for his pal Sandy. He bought a special
Flower Power fertilizer to see if it will help the plants
produce more flowers. He plants 2 plants of the same
size in separate containers with the same amount of
potting soil. He places one plant in a sunny window
and waters it every day with fertilized water. He
places the other plant on a shelf in a closet and waters
it with plain water every day.
What did SpongeBob do wrong in this experiment? Explain.
How can he test the effectiveness of the fertilizer?
Set up an experiment that tests this .
Super Snails
Gary is not the smartest snail in Bikini Bottom and
believes he can improve his brain power by eating
Super Snail Snacks. In order to test this hypothesis,
he recruits SpongeBob and several snail buddies to
help him with an experiment. The snails eat one
snack with each meal every day for three weeks.
SpongeBob created a test and gave it to the snails
before they started eating the snacks as well as after
three weeks.
Based on the data, do
the Super Snail Snack
work? Explain.
Set up the experiment
and list the procedure
he should use.
Snail
Before
After
Gary
Larry
Barry
Terry
64%
78%
82%
72%
80%
78%
84%
70%
Bubble Time
Patrick loves bubble gum and would like to
be able to blow bigger bubbles than
anyone else in Bikini Bottom. To prepare
for the Bikini Bottom Big Bubble Contest,
he bought five different brands of bubble
gum and he needs your help to find the
brand that creates the biggest bubbles.
Write an experiment to test the bubble power
of the bubble gum brands and help Patrick win
the contest.
Discussion Questions
1. What data would lead scientists to accept
the hypothesis in the experiment with the
robins’ eggs? What results might lead
them to reject the hypothesis? What
other variables might affect the results?
Using the data table in our notes, write out the
procedures that should be included in this
experiment.
A farmer believes that fertilizer runoff from a farm
is killing the fish in a nearby pond.
1. Set up an experiment to test his
hypothesis. Be sure to include all the
procedures he needs to follow.
The farmer measures the amount of fertilizer in
the pond each week and counts the number of
dead fish. The measurements indicate that, as
the fertilizer concentration increases, the
number of dead fish increases.
2. Can the farmer confidently conclude that
it must be fertilizer from the farm that
is killing the fish? Why or why not?