Applying the Scientific Method
Adopted & Modified from the Biology Laboratory Manual
Names of students in group
______________________________________________________________________________________
Directions: Before you begin any lab, always read the entire lab over from beginning to end before starting
to answer any questions or begin experimentation.
Observation- What do you see? Using your senses, describe what you see in front of you.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
Ask a Question
How will light affect the sprouting of eyes on a potato?
Introduction / Background Information
The scientific method is a procedure used to gather information and test ideas. Scientists use the scientific
method to answer questions about life and living organisms. Experimentation is an important part of the
scientific method. In order to ensure that the results of an experiment are due to the variable being tested, a
scientist must have both an experimental and a control setup. The experimental setup and the control setup
differ only in the variable being tested.
In this lab, you will use a potato to do a controlled experiment. Potato plants store starch in structures,
known as potatoes, which people dig up and eat. A potato is actually a tuber, an underground stem modified
for storage (Holt McDougal text, 2012). Figure 1 (http://lohitsascience.weebly.com/from-molecules-toorganisms5/6-observing-our-potato-plants) illustrates where the potatoes are located in relation to the rest of
the growing plant. Along the surface of a potato are buds, or “eyes,” which look like small dimples in the
potato skin. The “eyes” in a potato can sprout and grow into new potato plants because of vegetative
reproduction. Vegetative reproduction is a type of asexual reproduction in which stems, leaves, or roots
attached to the parent plant produce new individuals (Holt McDougal text, 2012). In your experiment, you
will determine whether more eyes sprout in the dark or in the light.
Figure 1. Potato plant.
Scientific Method Lab- Biology
Page 1
Pre-Lab Discussion Questions
1. Under what conditions do potatoes usually grow?
_________________________________________________________________________________
_________________________________________________________________________________
2. Why is it important to seal the plastic bags?
_________________________________________________________________________________
_________________________________________________________________________________
3. How does cutting one potato in half limit the variables of the experiment?
_________________________________________________________________________________
_________________________________________________________________________________
4. Why is it necessary to keep both potato halves on moist paper towels?
_________________________________________________________________________________
_________________________________________________________________________________
5. What evidence will tell you whether or not light is necessary for sprouting a potato?
_________________________________________________________________________________
_________________________________________________________________________________
Materials
Medium-sized potato
Scrub brush
Knife
Dissection tray
2 paper towels
2 plastic bags with twist ties
Permanent marker
Safety
When using the knife to cut the potato, keep your fingers out of the path of the blade. Wash your hands
thoroughly with soap and warm water after handling the potatoes.
Procedure
1. With the members of your group, discuss how the presence or absence of light will affect the
sprouting of a potato. Record the hypothesis you will test to answer this question.
a. Hypothesis:_________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
__________________________________________________________________________
2. Put on your safety goggles. Scrub the potato with a firm brush or your hand to remove any wax
coating that may be on the potato or dirt.
3. Using a tray carefully cut the potato lengthwise into equal halves. Assign one half to be put in the
dark and one half to be kept in the light.
4. Count the number of eyes on each potato half and record this information in the data table below.
5. Fold each paper towel until you have rectangles about equal in size to your potato halves. Moisten
the towels with water. Place a folded paper towel in each plastic bag.
6. Place a potato half in each plastic bag with the cut surface on the paper towel as shown in Figure 2.
Tie each bag with a twist tie. Use a permanent marker to label one bag Light and the other Dark.
Scientific Method Lab- Biology
Page 2
Figure 2.
7. Your teacher will designate a cool, dark place where you will keep one potato half and a cool, welllit place where you will keep the other. Place the bags in the appropriate locations. Make sure that
the potato halves are resting on top of the paper towels and that they are kept at the same
temperature.
8. After one week, open the bags and count the number of sprouts on each potato. Record the data on
the data table.
9. To calculate the percentage of eyes that sprouted, divide the number of sprouts by the number of
eyes and multiply the result by 100. Record your answers in the data table
10. When the experiment is over follow your teachers instruction for cleanup and disposal of materials.
Data Table
Location of
Potato
Dark
Light
Number of Eyes
Number of
Sprouts
% of Eyes
Sprouting
Using a sheet of graph paper to create a visual representation of your data.
Analyze and Conclude
1. Observing: Did more sprouts grow in the light or in the dark?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
2. Design an Experiment. What was the independent variable in this experiment? What was the
dependent variable?
_________________________________________________________________________________
_________________________________________________________________________________
Scientific Method Lab- Biology
Page 3
3. Design an Experiment. Which was the experimental setup in this investigation? Which was the
control?
Explain.__________________________________________________________________________
_________________________________________________________________________________
________________________________________________________________________________
4. Evaluate. Did the results of your experiment support your hypothesis?
Explain.__________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
5. What effect does light have on the sprouting of potatoes?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
6. Control Variables. Why was it important to keep both the control setup and the experimental setup
at the same temperature throughout the experiment?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
Extend Your Inquiry- Honors only.
Design an experiment to investigate whether temperature or amount of water affects the percentage of
sprouts. Before you begin, have your teacher approve your plan.
References
Nowicki, S. (2012). Biology Holt McDougal. Houghton Mifflin Harcourt Publishing Company.
smicbiology.weebly.com/uploads/8/7/6/2/8762809/scientific_method.doc
Scientific Method Lab- Biology
Page 4