Name ________________________
Date:__________________
Class:_________________
Identifying Your Variables – The Popcorn Lab
Problem - Question?
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Purpose:
 To learn the skill of writing a laboratory procedure – an important step
in the scientific method of lab experimentation

To demonstrate the ability to identify your variables by conducting the
Popcorn Lab.
Materials:
 3 Brands of Microwave Popcorn:
o Stop & Shop- $2.89, Orville Redenbacher’s - $3.69 &
Pop Secret - $3.29
 Bowls & cups
 Pen/pencil
 Paper
Hypothesis – Your initial prediction:
After conducting your background research, which brand of popcorn will pop
the most popcorn , leaving the least amount of kernels?
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Procedure:
1. Each group of students will be given 3 different brands of microwave popcorn
which has been previously popped.
2. Upon instruction from the teacher, each student will gently pour their 3 bags of
popcorn into separate bowls labeled A, B & C, carefully making sure not to mix up
the brands of popcorn into the same bowl.
3. Bowl A should contain the __________________________
Bowl B should contain the __________________________
Bowl C should contain the __________________________
4. After dispersing the popcorn bags into their proper bowls, you should then
count the leftover, unpopped kernels in each bag.
The unpopped kernels can be
placed in a cup as you are counting them.
5. Record your results in the data table below:
BOWL
A
B
C
-
Unpopped Kernels
Conclusion
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Questions
1. What differences did you observe between the unpopped and popped
popcorn?
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2. What is the Independent Variable in the Popcorn Lab?
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3. What is the Dependent Variable in the Popcorn Lab?
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4. What are the Control Variables in the Popcorn Lab? Why are they so
important to the experiment?
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5. List two additional testable questions using popcorn as the subject being
tested.
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6. Scientists must follow careful procedures to make sure their experiments
are safe, fair and easily repeated by other scientists. What step-by step
procedures will you follow to make sure that your popcorn brand test is safe,
fair and repeatable?
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Number of Un-popped kernels
Brand of Popcorn
Data from 5 Groups
Average amount of unpopped kernels among all
the Groups
Stop & Shop
Orville Redenbacher’s
Pop-Secret
Background Research
Popcorn is a type of maize which, unlike other types of corn, pops when
heated in oil or dry. It was first found and used to pop by Native
Americans thousands of years ago. The kind of popcorn most people
pop in their microwaves is the species Zea mays L subsp mays.
Christopher Columbus introduced popcorn to the West in the late 15th
century. As with other corns, popcorn has a certain amount of moisture
inside itself. But, unlike other corns, popcorn has a stronger outer hull
that doesn’t let moisture escape as fast as other corn when heated.
As the kernel is heated to the boiling point, water inside the kernel starts
to turn into steam, causing pressure inside the kernel to about 9 times the
pressure of air. Inside other types of corn - as well as damaged popcorn
kernels - the steam escapes the kernel as fast as it is formed. The
difference with popcorn is that the outer hull is strong enough to hold the
steam in, until it ruptures in a small explosion and turns it inside out, to
become the white fluffy stuff, better known as popcorn!
There are two explanations to why some kernels do not pop. One is that
the popcorn kernel just doesn’t have enough moisture to turn to steam.
The other explanation is the outer hull is leaky, and causes the steam to
escape before it can become super pressurized and explode the outer
hull. This could be caused by mishandling of the kernels at the factory,
or maltreatment of the kernels during shipment. The question is which
brand of popcorn handles the kernels the best at the factory and during
shipping and uses only the best corn?