Lesson 4:
Introduction to
Experimental Design
9/1 (A Day) and 9/2 (B Day)
DO Now:
1. Write two inferences to explain why
the person is lying on the ground.
For each inference site evidence
from the picture.
• Essential Question:
What makes the study of biology
different from all other disciplines?
• Objective: SWBAT conduct a
mealworm experiment in order to
identify and describe the elements
of a controlled experiment.
Lesson Overview
AGENDA
 Discussion/ Notes Experimental Design
 Misbehaving
Mealworms Lab
Setting the Stage
Some Like it Dark
HOMEWORK
 1.2 Methods of Biology
 Biology Notebook
Due 9/3 (A) & 9/4 (B)
*Next Class
Housekeeping
• Lab Safety
– You will not be able to
participate in lab until you turn
in a signed copy of your lab
safety contract
• Edmodo
– Class Name: Biology 20152016
– Group Code: 57beyu
• Biology Notebook (9/3, 9/4)
– Exam Grade
• Parent E-mail
– Extra Credit
Scientific Method
• Question
• Research
• Hypothesis
• Experiment
• Data/Results
• Conclusion
Experimental Design
• Plan an experiment in which you can test your
hypothesis.
• Experiment must be a controlled experiment.
– Test one variable at a time (experimental variable)
• Controlled experiments include two groups:
– Experimental group – receives treatment
– Control group – no treatment
• Variables
– Independent Variable: The factor that is deliberately
manipulated in an experiment (also experimental variable)
– Dependent variable: The variable that is changed or
effected by manipulation of the independent variable. It is
what is measure in the experiment
Repeatable and Reliable
• Constants
– Factors that must remain the same so they do not
influence the outcome of the experiment
– Accounting for constants ensures you are testing only
one variable
• Sample Size
– The number of subjects involved in experimentation
• Replications
– Decreases impact of chance events and error
– Increase reliability of results
Let’s Practice!
Problem:
• Which operating
system, iPhones
or Droids have a
longer battery
life?
Hypothesis:
Independent Variable:
Dependent Variable:
Control Group:
Experimental Group:
Let’s Practice!
Problem:
• Does the
temperature of a
lake effect a
fish's ability to
produce viable
offspring?
Hypothesis:
Independent Variable:
Dependent Variable:
Control Group:
Experimental Group:
Misbehaving Mealworms Lab
Setting the Stage
• create a circular area to observe
mealworms’ behavior
• use scissors to cut paper to fit the bottom
of dissecting pan
– Be sure to tape the sheet into the pan so
mealworms can’t crawl under paper
• trace a circle around bottom of 150 mL
beaker in center of paper
Some Like it Dark
• Do mealworms prefer light or dark
environments?
– fit piece of aluminum foil tightly across top of one
half of dissecting pan
– arrange pan so uncovered side is well-lit but
covered side is dark
– fold index card to use as a scoop
– use paintbrush to carefully brush 10 mealworms
onto card and transfer to 150mL beaker
– pour into circle
– observe 5-10 minutes
– record your observations