Title: “Egad!! What’s the Difference Between IV’s and DV’s?”
Author: Jodine Trout
Subject Areas: Scientific Method
Grades: 7th & 8th Grade
Description of the Lesson: Students often struggle with describing the Independent and
Dependent Variables, as well as the Control in an experiment. These lessons will give the
student practice in identification of these.
Length of the Lesson: Two 50 minute class periods
Student Objectives: The student will be able to review an experiment and cite the Independent
and Dependent Variables, as well as the Control
.
Materials: Several simple experiments in written and demonstration modes
Science Logs
Pencils, Pens, Colored Pencils
Science Textbooks
Handouts and library books with experiments
Pre & Post Test [at the end of this document]
Procedure:
1. Pass out pre-test and have students fill it in. Attached.
2. Ask students to explain what Independent Variables, Dependent Variables and the
Control mean in an experiment.
3. Set up the experiments on the pre-test and discuss the various ways to change the
experiments.
4. Have students draw the experiments A-C in their Science Logs, using colored
pencils and labeling the IV, DV and Control.
5. Students will pair up and explain the IV, DV and Control drawings to each other,
using correct vocabulary.
6. The “listening” student will record these three vocabulary words and judge the
explanation to be acceptable or not acceptable.
7. The “listening” student will defend their judgment to their partner.
8. All pairs will switch roles and repeat steps 5-7.
9. Students will present to the class and ask for feedback.
10. Students will choose experiments from their textbooks or other science materials in
the classroom and repeat steps 4 – 9, with new partners.
11. Repeat the process until the Instructor feels confident the class understands.
12. Give the post-test.
Scientific Explanation:
Independent Variable – the part of the experiment that is being tested
Dependent Variable – the part of the experiment that is being measured or observed
Control – the group in an experiment that nothing is done to
Assessment: Pre & Post Tests [included]
Kansas Standards:
STANDARD 1: SCIENCE AS INQUIRY Grades 5-7
SCIENCE AS INQUIRY – The student will develop the abilities to do scientific inquiry, be able to
demonstrate how scientific inquiry is applied, and develop understandings about scientific
inquiry.
Benchmark 1: The student will demonstrate abilities necessary to do the processes of scientific
inquiry.
Grades 5-7 Indicators The student….
1. ▲ identifies questions that can be answered through scientific investigations.
2. ▲ designs and conducts scientific investigations safely using appropriate tools, mathematics,
technology, and techniques to gather, analyze, and interpret data.
4. ▲ communicates scientific procedures, results and explanations.
Missouri Standards (GLE’s):
Strand 7.1 Concept A.1. Science understanding is developed through the use of science
process skills, scientific knowledge, scientific investigation, reasoning, and critical
thinking
Concept A. Scientific inquiry includes the ability of students to formulate a testable
question and explanation, and to select appropriate investigative methods in order to
obtain evidence relevant to the explanation
Pre-Test and Post-Test
Name ________________________________ Date ________________
1. In the following experiment, underline the independent variables.
2. In the following experiment, circle the dependent variable.
3. In the following experiment, make a rectangle around the control.
A. Question: Which liquid will affect the weight of the egg the most?
Weigh 6 eggs. Put an egg in 250 ml each of vegetable oil, orange juice, milk,
water, vinegar, Diet Coke. Wait 3 days.
B. Question: Which fertilizer will cause the plant to grow tallest in three
weeks?
Using the same type and size of plants, fertilize according to manufacturer’s
directions for four weeks. [Fertilizer brands: Miracle Grow, Wal-Mart,
Scott’s, Earl May fertilizers]
C. Question: What surface will cause the toy car to go farthest?
Using the same models of Matchbook cars, place them on an incline of 30
degrees. Each incline will have a different surface glued to it: sandpaper,
linoleum, ceramic tile, wood, wax paper, aluminum foil.
KEY:
QUESTION INDEPENDENT
DEPENDENT
CONTROL
A.
The liquids: vegetable oil, Weight of eggs Amount of
orange juice, milk, water,
liquid; size of
vinegar, Diet Coke
eggs
B
The fertilizer brands:
Height of plants Fertilizer
Miracle Grow, Wal-Mart,
schedule, water
Scott’s, Earl May
& sunshine
schedules
C.
The surfaces: sandpaper, Distance the toy Models of toy
linoleum, ceramic tile,
cars travel
cars, ramp
wood, wax paper,
incline and
aluminum foil
length
Best Answer - Chosen by Voters
An independent variable is a variable that is controlled or manipulated by you, the
researcher.
And a dependent variable is one that is caused or influenced by another.
--Wikipedia
Over the years I have become increasingly uncomfortable with the way many
people use the terms "independent variable" and "dependent variable." I now believe
that these terms should be used only when referring to experimental research, that is,
research where the independent variable(s) is(are) manipulated and the dependent
variable(s) is(are) passively observed. Researchers commonly associate the term
"independent variable" with "cause" and "dependent variable" with "effect." Using the
terms "independent variable" and "dependent variable" with nonexperimentally gathered
data may prod researchers in making causal attributions when they should not.
--- Karl L. Wuensch, Department of Psychology,
East Carolina University, Greenville NC 27858-4353
Here are the exact words from my study sheet.
EXAMPLE:
Does using Miracle Grow affect the growth rate of an Oak tree if you use Miracle Grow
once a week?
In this question the control group would be the Oak tree that you don't use Miracle Grow
on. The independent variable (sometimes known as the manipulated variable) is the
one factor changed in the experiment. Which, in this case is the Miracle Grow.
The dependent variable (sometimes known as the responding variable) is/are the
factor(s) or thing(s) that respond to the one change introduced by the independent
variable.
Most science investigations require a controlled experiment. A controlled experiment
is an experiment in which only one variable is tested at a time.
Investigations will often refer to both an independent and dependent variable.
Independent and dependent variables are related to one another.
The independent (or manipulated) variable is the variable that you, the experimenter,
change or manipulate intentionally.
Dependent (or responding) variable is the variable that changes when the
independent variable changes. The dependent variable depends on the outcome of the
independent variable.
Here are some simplified examples:
Question
Independent Variable
Dependent Variable
Does water help plants grow
best?
Type of liquid (water,
vinegar, etc)
Height of plant (in
cm)
What kind of teaching helps
kids learn best?
Type of instruction (reading,
lecture, video, lab)
Score on test
Does the form of sugar affect
how quickly is dissolves?
Form of sugar (granulated,
powdered, cube)
Time to dissolve (in
seconds)
With each of these experiments, it is very important to control the experiment.
Question 1: You ONLY want to test the TYPE of liquid. Imagine you watered one plant
with water every day and another plant with vinegar every other day. If you found the
plant given vinegar grew less tall, you wouldn't know if it is because of the type of liquid
or the frequency of which you watered the plant. There are TOO MANY VARIABLES.
Kids will relate to this being a "fair" comparison or not. In this investigation, the
following variables must be kept the same between the two plants: the type of plant,
size of container, amount of sunlight each day, temperature, amount of liquid, how
frequently the plant is watered… etc. These variables that are kept the same are called
controlled variables.
Of course, we cannot control everything in an experiment. We may have the same
types of plant, but one seed was not as robust. Perhaps when we planted the seed,
one seed was slightly deeper in the pot than the other. These types of control mishaps
constitute "experimental error."
Read more about variables and controls at:



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ScienceBuddies.com
National Center for Educational Statistics (NCES)
Kids' page
CoolScienceProjects.com
Science Kids (more elementary)