Pill Bug Habitat Preferences
Designing Your Own Experiment
We need to collect and bring in Pill Bugs and
Sow Bugs!!! We will use them in experiments that
we design ourselves next week!
While most people
call them pill bugs,
they are also called
doodle bugs and
rolly pollies, which
has various
spellings.
Sow bugs are very similar
in appearance, but they
do not roll up into a ball
when disturbed.
Where can you find Pill Bugs and Sow Bugs?
Isopods breathe with gills, so pill bugs and sow bugs,
although they live on land, they are restricted to areas with
high humidity, under rocks or logs, in leaf litter or in crevices.
They prefer shady areas, and some species are nocturnal.
Therefore, the recommended way to search for some would
be after dark, in areas that during the day are shady, under
some logs in some very moist soil.
To attract them, water
soil or leaf litter in the
shade and cover with
plastic, piece of
plywood or cardboard.
Keep the area moist
and check under the
covering in a couple
days.
How to collect – have fun!
Before looking for isopods, prepare a container and tools to gather
the isopods.
To collect them, use a spoon or shovel and a container. Look under
a rock or log and be prepared to collect the isopods quickly before
they scurry away from the light.
Gently scoop up soil with the isopods and place them in the
container. Look on the underside of the log or stone for others. They
can be gently picked or brushed off with a finger into the container.
Pill bugs often curl up and can be picked up individually or scooped
up with the spoon.
If you are going to keep the isopods a couple days before placing
them in the classroom, use a plastic margarine or cottage cheese
container with small holes poked in the lid and a moistened piece of
paper towel lightly crumple inside. Use an old pie tin to sort the
isopods from the soil before placing them in the container. The
paper towel must be kept moist or they will die. A slice of potato
or apple will provide the pill bugs with both food and moisture.
Pre-Lab Activity
Answer each of the following questions.
1. What is the difference between qualitative
and quantitative data?
2. What is an independent variable?
3. What is a dependent variable?
4. What is the difference between a control
and an experimental group?
5. Describe the environmental conditions in
the places where you found your pill bugs.
1. What is the difference between
qualitative and quantitative data?
2. What is an independent variable?
3. What is a dependent variable?
4. What is the difference between a
control and an experimental group?
5. Describe the environmental conditions in
the places where you found your pill bugs.
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
• To understand how to gather and record scientific
data, both qualitative and quantitative
• To learn about pill bug behavior
Instructions
Step one: Initial observations
Observe the pill bugs for 5 minutes 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 in your Data
section.
Instructions continued
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. Your
experiment should help to determine pill bug habitat preferences.
Consider where you found your pill bugs as well as your initial
observations when choosing your independent variable.
1.
2.
3.
4.
5.
6.
Name the independent variable of your experiment (the one that you
will manipulate).
Name the dependent variable of your experiment (the one that you will
measure).
Now, state your hypothesis in terms of the effect you expect the
independent variable to have on the dependent variable. Use the
following format: If (the independent variable is manipulated in this
way), then (the dependent variable will respond in this way).
What will be your control for your experiment?
What will be your experimental group?
How many replicates or trials will you carry out, and why?
Constructing a Good Hypothesis
3. Now, state your hypothesis in terms of the effect you expect
the independent variable to have on the dependent variable.
Use the following format: If (the independent variable is
manipulated in this way), then (the dependent variable will
respond in this way).
Constructing a Good Experiment
from a Good Hypothesis
4. What will be your control for your experiment?
5. What will be your experimental group?
6. How many replicates or trials will you carry out, and why?
Instructions continued
7. Draw a quick diagram below of what your experimental set-up
will look like, and label everything.
Instructions continued
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. Be sure your
procedure takes into account each of the following:
•independent and dependent variables
•control and experimental groups
•how long, how many, etc.
•method for data collection
Instructions continued
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.
Conclusions
Use the following as a guide in writing a conclusion to this lab.
•Briefly explain what they lab was and what your hypothesis was.
•State if your hypothesis was supported by the results, or not
supported by the results? Give the reasons why or why not.
•Now that you have done the experiment, what do you know now
that you wish you knew before you started? Would these be things
that you would change about your experimental design before
doing the experiment again?
•What are some possible sources of human error in your
experimental results? (ONE SENTENCE).
•Did the results of your experiment lead you to ask more questions
about the behavior of the pill bug? What are some new hypotheses
you have as tentative explanations for pill bug behavior?