Lab 6
Intro Biology
Laboratory: Pill Bug Behavior! Designing our own Experiments
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Pre-lab: Answer the following questions.
1. What is the difference between qualitative and quantitative data? ______________________________
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2. What is an independent variable? ________________________________________________________
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3. What is a dependent variable? __________________________________________________________
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4. What is the difference between a control and an experimental group? ___________________________
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5. What are replicates? Why are they done? _________________________________________________
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Purpose: To design and carry out an experiment using the crustacean animal called a pill bug (a.k.a. sow
bugs and roly-polies) to learn about their behaviors, as well as to learn how to design scientifically valid
experiments.
Objectives:
• To gain experience and understanding about the importance of experimental design
• To gain experience in forming and revising hypotheses
• To demonstrate the use of a control and replicates/trials in an experiment
• To be able to identify the independent and dependent variables in an experiment
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To understand how to gather and record scientific data, both qualitative and quantitative
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To learn about pill bug behavior
Materials:
6 or more pill bugs per group
animal behavior choice chambers
Scrap paper of different colors
paper towels
aluminum foil
Ice
lamps
Laboratory
Step one: Initial observations
Observe the pill bugs and take note of their behavior. Try introducing them to some new situations, and
see how they react! Begin generating some ideas for a hypothesis to test. Note some of your initial pill
bug observations below.
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Lab 6
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Step two: Design your experiment
Based on your initial observations recorded above, decide what you would like to test, and determine
what your variables are.
1. Name the independent variable of your experiment: _______________________________________
2. Name the dependent variable of your experiment: _________________________________________
3. Now, state your hypothesis in terms of the effect you expect the independent variable to have on the
dependent variable:
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4. What will be your control group for your experiment?
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5. What will be your experimental group?
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6. How many replicates and trials will you carry out, and why?
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7. Draw a quick diagram below of what your experimental set-up will look like, and label
everything.
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Step three: Write out your experimental procedure
Scientists need to write down everything they are going to do during an experiment. They need to include
enough details that someone else can carry out the experiment in exactly the same way, just by reading
the procedure and not having to consult with the scientist. Decide on and record your experimental
procedure for carrying out your experiment below. You may wish to list your procedure as a series of
steps to take.
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Step four: Set up your data table on a separate piece of paper
Based on your experimental design and your procedure, you need to set up the appropriate number of
rows and columns for your data table, in order to record quantitative data. Decide what you will be
recording, and what you will label the rows, and what you will label the columns. Below your data table,
leave some room for the recording of some qualitative data (written out in sentences).
Step Five: Set up your experiment according to your diagram, carry out your written
procedure, and record your data (your results) in your data table.
Step Six: Graph your data. Use a bar graph if you are comparing categories or a line
graph if you are measuring something over time. Don’t forget to label the axes with a
title and units and also give the graph a # and title!
Step seven: Complete a formal lab report. Follow the guidelines for writing a formal
lab report and look at the Water Strider Sample lab report to help you write your
first formal lab report!