Article of the Week - due Mon., March 9
Mastery: __________/12
Name ______________________________
Habits: _____/6 On time ___ Complete ___ Annotation ___ Parent signature ___
Scientists study mystery of popcorn: why does it
jump and make noise?
By the Los Angeles Times, 02.22.15
(1) When you make popcorn in the
microwave, something quite unique
happens. A kernel turning into a fluffy
white treat actually goes through an
exciting scientific transformation.
(2) Many people do not understand that
popping kernels is rather complicated.
Two researchers from France were
fascinated by this process. The popping of
In this image taken on Jan. 28, 2013, Stovetop Popcorn
corn is a reminder that science applies to
Many Ways is shown served in a bowl in Concord, New
everything around us — even snack food.
Hampshire.
(3) Researchers Emmanuel Virot and Alexandre Ponomarenko used physics to study the
phenomenon of popcorn popping. They recently published a study on popcorn.
Why Does It Jump And Pop?
(4) Until now, most research on popcorn has been focused on simple questions. For example,
chemists determined how much moisture a kernel needs to pop. Other scientists studied the
shape of kernels. They found the ideal shape for an unpopped kernel is to be round. Other
researchers figured out how to reduce the number of kernels that don't pop in a batch of
popcorn.
(5) Virot and Ponomarenko aren’t interested in improving the taste or experience of popcorn.
Instead, they wanted to know more about what causes popcorn to act and taste like it does. They
especially wanted to learn what makes popcorn jump and why it makes that pop-pop-pop sound.
(6) The scientific name for popcorn is Zea mays everta and it is the only type of corn that pops.
Popcorn kernels are rounder than other corn kernels. There is a thin layer, or hull, that covers the
seed. Inside the seed is the kernel's endosperm. The endosperm is a starch that provides food
(energy) for the living part of the kernel, known as the germ or embryo.
Thousands Of Pictures
(7) When the kernel gets very hot — above 100 degrees Celsius (212 degrees Fahrenheit) — the
water inside hits its boiling point and turns to steam. The steam creates a vapor that forces its
way into the endosperm. The endosperm melts into a thick substance, like bread dough. The
vapor puts pressure on the hull as the heat is increased. Eventually, the hull cannot take the heat
anymore. The kernel has to explode.
(8) The starch cools very quickly as soon as the kernel explodes. It turns into a spongy white flake
of popcorn. After this popping process, the fluffy corn is twice as large as the original kernel.
(9) Virot and Ponomarenko used high-speed cameras to capture this process very closely. They
used the cameras to observe kernels popping on a hot plate. They turned the heat and placed a
few kernels on the very hot surface. The cameras took thousands of pictures every second.
A Quick Kick
(10) It took them hundreds of tries to figure out what made the kernels jump. At first, they
thought the steam makes the kernel jump, but that turned out to be wrong. They eventually
discovered that a small "leg" pops out from the broken hull. The leg kicks the kernel into the air.
When the leg is released, the popcorn moves like a gymnast somersaulting. All of this happens
very fast, in just one-fifteenth of a second.
(11) After studying these small movements, the French team was able to conclude what
temperature the kernels needs to pop. They put kernels of microwaveable popcorn in an oven
and turned up the temperature slowly. Each time they cranked it up, the temperature increased
50 degrees. Almost all of the kernels popped when the heat reached 180 degrees Celsius (356
degrees Fahrenheit) — no matter how big or small the kernel was.
(12) Finally, they investigated why the popcorn makes the pop-pop-pop sound as it heats up.
Look, Listen, Then Taste
(13) They brainstormed three possible reasons for the noise. They thought it happened when the
hull cracked, when the kernel bounced after exploding, or when the water vapor was released. To
figure out the right answer, they used microphones to study when exactly the popcorn made the
noise. They put the microphones very close to the hot plate, and used the cameras as well.
(14) There was no sound when the popcorn first opened, which told the researchers that the hull
was not causing the noise. Soon, they realized that the hull actually cracks twice. They heard the
pop noise 6 milliseconds after the second crack.
(15) They used the process of elimination to conclude that the trigger for the popping sound was
the release of water vapor.
(16) At the end of a long day of experiments, the researchers would usually enjoy a snack of the
popcorn they tested together.
Article of the Week Questions
Due Monday, March 9
Name ______________________________
Read each question carefully, then write your answer in the blank. (6 points)
_______ 1. Read the sentence from the section "A Quick Kick."
It took them hundreds of tries to figure out what made the kernels jump.
Which sentence explains why figuring out what made the kernels jump was so difficult?
A. At first, they thought the steam makes the kernel jump, but that turned out to be wrong.
B. All of this happens very fast, in just one-fifteenth of a second.
C. Almost all of the kernels popped when the heat reached 180 degrees Celsius (356 degrees Fahrenheit) — no
matter how big or small the kernel was.
D. They put kernels of microwaveable popcorn in an oven and turned up the temperature slowly.
_______ 2. Which sentence explains the main method the researchers used to study the popcorn popping?
A. When the kernel gets very hot — above 100 degrees Celsius (212 degrees Fahrenheit) — the water inside
hits its boiling point and turns to steam.
B. Finally, they investigated why the popcorn makes the pop-pop-pop sound as it heats up.
C. Virot and Ponomarenko used high-speed cameras to capture this process very closely.
D. They used the process of elimination to conclude that the trigger for the popping sound was the release of
water vapor.
_______ 3. Which selection explains the main topic of the article?
A. Until now, most research on popcorn has been focused on simple questions. For example, chemists
determined how much moisture a kernel needs to pop.
B. The scientific name for popcorn is Zea mays everta and it is the only type of corn that pops. Popcorn kernels
are rounder than other corn kernels.
C. Instead, they wanted to know more about what causes popcorn to act and taste like it does. They especially
wanted to learn what makes popcorn jump and why it makes that pop-pop-pop sound.
D. Inside the seed is the kernel's endosperm. The endosperm is a starch that provides food (energy) for the
living part of the kernel, known as the germ or embryo.
4. Identify the paragraph on the first page that describes prior research on popcorn.
Write the paragraph number here: _______
_______ 5. Which of the following sentences is a fact rather than an opinion or judgment?
A. When you make popcorn in the microwave, something quite unique happens.
B. Many people do not understand that popping kernels is rather complicated.
C. Researchers Emmanuel Virot and Alexandre Ponomarenko used physics to study the phenomenon of
popcorn popping.
D. The popping of corn is a reminder that science applies to everything around us — even snack food.
_______ 6. Read the sentence from the section "Look, Listen, Then Taste."
They brainstormed three possible reasons for the noise. They thought it happened when the hull cracked, when the
kernel bounced after exploding, or when the water vapor was released.
Which of the three reasons turned out to be correct?
A. the release of pressurized water vapor
C. the cracking of the hull
B. the bounce of the corn on the ground
D. none of the above
For each statement below, circle/shade in whether the text/author would agree or disagree with it, and in the
space provided, give a quote from the text and explain how it supports your answer. (6 points)
Agree?
yes
no
yes
no
yes
no
Statements
Your Evidence (quote, paragraph #, briefly explain)
1. The science behind
popcorn popping is
exciting.
2. The researchers were
particularly interested in
how to improve the
taste of popcorn.
3. Conducting this
research made the
scientists dislike
popcorn.
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