Biology 101: Experimental Design Worksheet - Scientific Method

This document is an experimental design worksheet designed to reinforce understanding of the scientific method. It begins with definitions of key terms like hypothesis, independent variable, dependent variable, control group, and experimental groups. The worksheet then provides practice problems where students formulate hypotheses and identify variables, control groups, and experimental groups for various scenarios, such as cigarette smoking and lung cancer, and the impact of breakfast on school performance. It also includes a situation-based experiment design problem involving shark attacks, requiring students to formulate hypotheses, identify materials, and determine variables. Further practice problems cover plant growth in different light colors, deer population changes, and student study habits. Finally, the worksheet presents additional scenarios to identify independent and dependent variables and the type of study design used. The document emphasizes the importance of controlling variables and designing experiments to test hypotheses. The assignment explores concepts like experimental and control groups, independent and dependent variables, and the scientific method.

Experimental Design Worksheet
Complete this for practice and message the instructor with your completed sheet for the answers.
Definitions: Define the following words and concepts related to the scientific method.
1. Hypothesis: This is proposed or supposed explainaination for a phenomenon in scientific study.
2. Independent Variable: This is the variable that doest not depend on another
3. Dependent Variable: This is the variable that depend on another.
4. Control Group: This separated experiement from the rest in which the independent variable tested doesnot
influence the results.
5. Experimental Groups: this is the group receiving treatment in an experiement.
Practice: Write a hypothesis for each of the statements and identify the variables, control group, and
experimental group.
1. Cigarette smoking increases the risk of lung cancer.
Hypothesis: If people smoke cigarettes, then their lung cancer risk increaese
Independent Variable: Amount or the rate of smoking cigarrate
Dependent Variable: Lung cancer risk
Control Group: None cigarette smokers
Experimental Group: People who smoke cigarette
2. Eating breakfast increases performance in school.
Hypothesis: If students eats breakfast then they increase their level of academic perfoamnce in school increases
Independent Variable: Eating breakfast
Dependent Variable: Academic performance in school

Control Group: Students who does not take breakfast
Experimental Group: students taking break fast
3. Hummingbirds are attracted to the color red.
Hypothesis: If the birdfeeders are painted red, then they will attract hummingbirds
Independent Variable: color of the birdfeeders
Dependent Variable: the number of the hummingbirds attracted
Control Group: birdfeeders that are not painted red color
Experimental Group: birdfeeders colored red
4. Bats locate food using sound waves.
Hypothesis: If the bats hear sound waves, then they will be attracted to that sound
Independent Variable: sound waves
Dependent Variable: the unit or number of the bats
Control Group: unavailability of sound waves
Experimental Group: sound waves
5. iBook batteries last for 5 hours.
Hypothesis: If one use the iBook batteries, then his or her iBook will run for five hours
Independent Variable: type of the batteries
Dependent Variable: time plays
Control Group: other different types of batteries
Experimental Group: iBook batteries
Situations: Read the situation below and design an experiment.
John Smith has been hired by the city of Virginia Beach to investigate the recent shark attacks off the resort’s

coast. He has a budget of $40,000, a 25 foot boat, and three graduate student assistants to help him. A
helicopter has also been donated by a local television station, should he need one.
* * *
1. List 2 hypotheses John and his crew may have come up with for the recent shark attacks.
a. If swimmers wear bright colored swimming suits, then they will be attacked by shark
b. If the population of fish decreases, then the rate of the shark attack will increase
2. What materials will John need to perform this experiment (How will they spend the $40,000?). bright
swimming suits, floating devices, dark swimming suits, manikins.
3. Where should they perform the experiment (Hint: Where do sharks like to live)? Deep beaches
4. Pick one of the two hypotheses and determine the following:
a. Control Group: dark swimming suits
b. Experimental Group: bright swimming suits
c. Dependent Variable: number of the shark attacks
d. Independent Variable: color of the swimming suits
5. What type of data do you think John will collect (What will be the results of the experiment?)?
The number of the attacks by sharks
6. What conclusions will John be able to make from the results of the experiment? If wearing the bright
swimming suits incraeses the number if the attacks by the sharks
In the statements below, write the hypothesis, variable, control groups and experimental groups.
1. Plants grow best in white light.
Hypothesis: If the plants are grown in the white light, then they will grow very tall

Independent Variable: light type
Dependent Variable: height of the plants
Control Group: plants within different light colors
Experimental Group: plants in white color light
2. The deer population decreases in the winter due to the lack of food.
Hypothesis: If there is lack of food, then the population of the dear will decrease
Independent Variable: amount of food
Dependent Variable: number of dear
Control Group: a lot of food
Experimental Group: lack of food
3. Students who study perform better in school.
Hypothesis: If the students studies, then they acquire good grades
Independent Variable: studying
Dependent Variable: grades
Control Group: not studying
Experimental Group: studying
Read the following situation and answer the following questions.
Suzie Q wants to know the effect of different colors of light on the growth of plants. She believes that plants
can survive best in white light. She buys 5 ferns of the same species, which are all approximately the same age
and height. She places one in white light, one in blue light, one in green light, one in red light and one in the
closet. All of the ferns are planted in Miracle-Grow and given 20 mL of water once a day for 2 weeks. After
the two weeks, Suzie observes the plants and makes measurements.

Hypothesis: If the ferns receives white light, then they will survive best
Independent Variable: different light colors
Dependent Variable: the growth rate of the ferns plants
Control Group: ferns place in place with no lighht
Experimental Group: ferns exposed to light
What types of measurements can Suzie make on the plants to determine how they did in different types of
light? Ferns should be from the same species, planting all ferns in Miracle-Grow, giving 20 mL of the water
each day.
Experimental Design Worksheet Name ______________________________
Scientific Method Period ___________ Date______________
Identifying Independent and Dependent Variables, and Study Designs
Additional Practice Problems
Instructions: For each research description below, identify the independent variable, the dependent variable, and
the type of study (lab experiment, naturalistic observation, survey, or case study).
1. A researcher hypothesizes that blondes really do have more fun. To test this hypothesis, she interviews
a natural brunette who has recently become a blonde to determine if there is any change in the amount
of fun she has.
Independent variable: hair color
Dependent variable: fun
Type of study: Case study

2. A developmental psychologist is testing the hypothesis that children in first grade know more words in
the English language than children in Kindergarten. To test this, she sits in on two classes (one first
grade, the other Kindergarten) and counts the average number of words children in each class speak.
She then compares the counts.
Independent variable: grade level
Dependent variable: number of the words
Type of study: Naturalistic observation.
3. A clinical psychologist hypothesizes that people who have been diagnosed as having major depression
will be more likely to also be diagnosed with an anxiety disorder than will people who have not been
diagnosed with major depression. To test this, he gives a survey to 100 people being treated for
depression and 100 people with no known mental disorder. The survey asks them to report whether or
not they have been diagnosed as having an anxiety disorder.
Independent variable: having depression or not
Dependent variable: having an anxiety disorder
Type of study: survey
4. A pharmacologist is testing whether a new anti-anxiety medication, Moodcor, will cause people to gain
weight. To test this, she gives 100 people Moodcor for one month and 100 people a placebo drug. At
the end of the month, she monitors any weight gain.
Independent variable: receiving medication
Dependent variable: Weight gain
Type of study: Lab experiment
5. A developmental psychologist believes that if children successfully lie to their friends, they will be more
likely to try lying to their parents. To test this hypothesis, he asks 50 children to report how many times
in the last month they have lied to their friends, and whether they were successful. He then asks them
how many times they have lied to their parents.
Independent variable: Successfully lying to friends

Dependent variable: Lying to parents
Type of study: survey study
6. A personality psychologist believes that people who are more aggressive are more likely to purchase
sports coupes than people who are less aggressive. To test this, he visits local car dealerships and asks
car shoppers to complete an aggression survey. Then, he observes what types of cars they purchase
(sports coupe, sedan, SUV, or pickup).
Independent variable: Aggressiveness
Dependent variable: If a sports coupe is purchased
Type of study: survey study
7. A clinical psychologist hypothesizes that listening to an inspirational tape will lead one to be in a better
mood. To test this, she has 50 people listen to an hour-long inspirational tape. Another 50 listen to
white noise for an hour. She then has them rate their mood on a 10-point scale.
Independent variable: if one listens to the inspirational tape or the white noise
Dependent variable: Mood
Type of study: Lab experiment
8. A clinical psychologist is testing his theory that people who experienced a brain injury are
developmentally delayed to the age at which they experienced the injury (for instance, if one has a brain
injury at the age of 10, that person will always act like they are 10). To test this, he conducts
developmental interviews with two people who experienced a brain injury at two different ages (one
was 3 and one was 20).
Independent variable: Brain injury
Dependent variable: Age one is developmentally delayed
Type of study: Case study