Category: Cobb Vicki

The Battle Hymn of the Chicken Pox Troopers

5/23/2022

Vicki Cobb
The Master Chef of Kids’ Hands-on Science

How does a virus cause a disease? A virus is not a complete living thing. It is like a free-floating nucleus of cell. It doesn’t “grow” but under certain conditions it can make a copy of itself or reproduce. It invades the cells of other living things to use the internal structure of the host cells to reproduce. At a certain point, the number of new viruses in a cell is so large that the cell ruptures and dies, spilling out newly made viruses to continue the invasion to other uninfected cells.

One virus we understand very well is chicken pox. Chicken pox is a very contagious disease that enters the body through the air and affects mostly children. When I was young almost every kid got chicken pox but, since 1995, there has been a vaccine, which makes you immune and protects the spread of the disease to others. Is there another way to explain how this virus works? Suppose I imagine a virus could think, which it can’t. But, imagination gives me the freedom to think differently.

So I wrote a poem about an army of chicken pox viruses as they are about to attack a human being, maybe you, my reader. A “battle hymm” is a chant or a song to rally the troups just before an attack.

The Battle Hymn of the Chicken Pox Troopers

Charge forward, fellow viruses!
Invade a cell or two
Then let us join together
And make a chicken pox on you.

Let cells try to fight us
No matter what they do
Red spots of our graffiti
Make a chicken pox on you

We make the top skin separate
And fill the space with goo,
Small, itchy blisters are a stage
Of chicken pox on you.

And when the blisters break, my friend
You think perhaps we’re through
But no. Now there is a scab
For each chicken pox on you

Scratch a scab so it comes off
Baring skin that’s raw and new,
A scar forever marks the spot
Of that chicken pox on you.

The source? Chicken with fowl pox

To the battle, fellow viruses!
We’re more noteworthy than flu
They just make you feel sick
We make our chicken pox on you!

Meet your personal superheroes - your body's cells Superhero cells rally together to battle common childhood ailments in this series in which Vicki Cobb explains how your amazing human body heals itself and fights off intruders. Here's her book on yet another virus: Your Body Battles a Cold.

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Banging on the Ear Drum

5/16/2022

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Vicki Cobb

The Master Chef of kids’ hands-on science

Ever notice people wearing headsets to keep out noise? Check out the workers on the tarmac of airports, or gardeners with their leaf blowers, or road workers breaking up blacktop with a pneumatic drill. They wear these headsets to protect their ears from damage caused by persistent loud noise.

Loudness is measured in decibels, dB for short. Complete silence is 0 dB, a whisper is 10 dB, normal conversation is 60 dB or about 10,000 times louder than a whisper. A lawnmower is 90 dB, about 1,000 times louder than a conversation and a jet engine is 120 dB about 1,000,000 times louder than a conversation. Anything over 85 dB does damage to our ears. That’s because sound traveling through air is a force beating against delicate eardrums. Yes, rock concerts damage ears.

Performing musicians often have tiny earpieces in their ears. This way the sound engineers can send them the sounds of their own voices or instruments, so that they can hear themselves over the other musicians. Those pieces are not for protection. So the dB level of rock concerts can affect those musicians’ hearing. There is even a name for it: Noise Induced Hearing Loss or NIHL. Rock musicians are the top profession to suffer NIHL later in life.

But there is a new threat to hearing loss—the earbuds people use to listen to music from their electronic devices. They are fine if you keep the volume down. But if you’re hooked on loudness that invades all your senses so that you can’t “hear yourself think” and you listen for several hours a day, you’ll pay the price down the road.

Your ability to hear high tones is the first to go. Here’s a quick and easy hearing test you can use on yourself and your family: Turn on the TV and hit the “mute” button or turn the volume all the way down. Lean over the back of the set and listen for a very soft, high-pitched whine. If you can hear it, you are listening to the highest sound the human ear can hear. (Dogs, of course, can hear much higher sounds, hence the dog whistle, which people can’t hear but dogs can.) Walk away from the set to find the distance when you can no longer hear it. Do the same test with your parents. Bet your hearing is better than theirs.

Try listening to some old-fashioned, melodic, soft popular music that came before rock and roll. You just might like it.

Listening to her own soft music, or just blocking out your loud music? Either way, her hearing is better than yours. Photo by Alexandra Siy

From School Library Journal--
"Fun!" comes through loud and clear in this energetic exploration of hearing and auditory perception. Cobb gets the anatomy lesson out of the way, then moves on to a series of simple activities to help kids experiment with their own sense of hearing. Students investigate sound conduction, perception of pitch, echolocation, and range of hearing by doing such things as sticking fingers in their ears while they talk."
Available for download at the i-Tunes store -- click here.

Vicki Cobb is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Cobb, Vicki. "Banging on the Ear Drum." Nonfiction Minute, iNK Think Tank, 30
Apr. 2018, www.nonfictionminute.org/the-nonfiction-minute/Banging-on-the-Ear-Drum.

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Why You Can’t Defrost a Salad…Yet

5/2/2022

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Vicki Cobb
The Master Chef of Kids' Hands-on Science

At left in the back is a fresh spinach leaf that has been treated with trehalose, frozen and defrosted.. The droopy one has been frozen and defrosted without trehalose. It's what is giving us hope that we may soon be able to defrost a salad.

When it comes to preserving a fresh taste in food to be eaten at some later time, nothing beats freezing it. That was the discovery made by Clarence Birdseye in 1924. He had been working in northern Canada and noticed that fish caught by the native Canadian Inuits froze almost instantly in the frigid winter air. It was just as delicious when cooked and eaten months later as it was on the day it was fresh. Birdseye figured that if food was frozen quickly at very cold temperatures, large ice crystals couldn’t form to damage the food and make it mushy. His flash-freezing process made him very rich.

The problem isn’t so much the freezing of food as what happens when it’s defrosted. See for yourself. Stick a stalk of celery in your freezer. The next day defrost it. Want to eat it? Compare it to a fresh unfrozen stalk. The perky structure of fresh celery is destroyed by ice. Water has the very unusual property of expanding and taking up more space when it changes into ice than when in a liquid state. That’s why ice cubes float and frozen unopened soda cans bulge.   Expanding ice crystals destroy the cell walls of plants. Quickly freezing fresh food keeps the ice crystals smaller than slower freezing, but they are still large enough to destroy the cell walls of delicate vegetables like spinach or lettuce. But if you defrost frozen spinach from the supermarket it is beyond limp. So a salad you can defrost and serve as if it were fresh has seemed like an impossible dream.

Federico Gomez, a Swedish scientist, is working to change this. Like Birdseye he took a close look at nature, specifically at plants that stay alive in very cold climates. He discovered that they contain a sugar called trehalose (tree-HAL-ose) that works like a natural antifreeze. Could he find a way to get trehalose into spinach leaves? If so, would the trehalose protect the structure of the spinach and keep it crisp after defrosting? This picture shows the results. The leaf on the left was treated with trehalose. The one on the right was untreated. He froze and defrosted both. The treated leaf is as crisp as if it had never been frozen!

Just because there is success in a lab doesn’t mean a defrosted salad will show up on your dinner plate any time soon. But these results are enough to keep the research going.

Move over Clarence Birdseye!

This is a nice fresh, crisp piece of celery...

...and this is the same piece of celery after being frozen and then defrosted. Yuk!

Cobb has revised her classic book, Science Experiments You Can Eat. While doing her research, she came across this work of Frederico Gomez. She bought trehalose on line and soaked some slices of parsnip and zucchini in a trehalose solution, hoping that the sugar would be absorbed by the plant cells. But when she froze them and defrosted them, it didn't work. Dr. Gomez got the sugar inside the plant cells by removing some water from between the cells in a vacuum chamber, soaking the leaves in a trehalose solution (which moved the sugar into the spaces outside the cells) and then exposing the leaves with a mild electric shock to get the sugar through the cell walls. Vicki didn't have the equipment to do all this but she tried anyway. The book was published in 2016.

Vicki Cobb is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Cobb, Vicki. "Why You Can't Defrost a Salad...Yet." Nonfiction Minute, iNK Think
Tank, 11 01 2018, www.nonfictionminute.org/the-nonfiction-minute/
Why-You-Can't-Defrost-a-Salad-Yet.

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How to Make Your Friends Think You're Super Strong

4/7/2022

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Vicki Cobb

The Master Chef of Kids' Hands-on Science

No one wants to mess with someone who is super strong! Even if you’re undersized, especially if you’re undersized, you’ve got to try the two tricks in this Minute .

Here’s the first challenge:  Bet another person can’t remove your hand from the top of your head.   The challenge-taker must try to remove your hand according to your rules. Otherwise, it’s cheating. Sit on the floor. Place your hand with your fingers spread apart firmly on the top of your head. Have your friend grasp your lower arm next to your elbow. Now let him/her pull upward, trying to lift your hand from the top of your head.

Chances are excellent that you’ll be lifted off the ground before your palm parts from its perch.

Why is this so? If you’ve studied simple machines you may have learned about a mechanical advantage. That’s how a simple machine such as a lever can multiply your strength or speed. In this case, you’re putting your friend at a mechanical disadvantage.   Your arm is a lever. In order to move your hand from the top of your head, you need an upward force near your hand. If that force is delivered as far away from your hand as possible, it loses its power. It’s easy to remove your hand if you deliver an upward force near your wrist. But at your elbow? No way! Got it?

Here’s another trick with the secret sauce of physics. Bet you can keep ten people from shoving you into a wall. Place your hands against a wall with your fingers spread and your arms outstretched. Have ten people line up behind you, hands on the shoulders of the person in front of them. At the count of three, have everyone push on the person in front of them as hard as they can. I mean, really lean in.

You, hero of the day, can hold them all off and not bend your elbows.

Why? Actually, each person absorbs the force of the person behind them so that you are not experiencing the cumulative force of ten people, only the force of the person directly behind you. So pick someone smaller than you to be that first person.   If you’re not super strong, you can still be super smart.

If you don’t want to try this yourself, look at my videos of other people doing the challenges. Maybe you’ll change your mind.

If you like these bets, check out Vicki Cobb’s new release of We Dare You! You might want to join her We Dare You! National Video Project and make more videos yourself from her book. Learn more about it here.

Vicki Cobb is a member of iNK’s Authors on Call. You can invite her to your class through the magic of videoconferencing. Learn more about it here.

MLA 8 Citation
Cobb, Vicki. "How to Make Your Friends Think You're Super Strong." Nonfiction
Minute, iNK Think Tank, 23 Mar. 2018, www.nonfictionminute.org/
the-nonfiction-minute/How-to-Make-Your-Friends-Think-Youre-Super-Strong.

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A Bouncing Ball Like You've Never Seen

3/29/2022

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Vicki Cobb
The Master Chef of Kids’ Hands-on Science

You can’t play tennis unless you know where the ball will be after it bounces. You can’t pass a basketball unless you understand how to angle a bounce so that it goes where you want it to go. As long as the court surface is smooth and flat, a ball’s bounce is very predictable. Its path depends on gravity and on the strength and direction of the force that sets the ball in motion. Thanks to high speed photography we can get a closer look at a bouncing ball.

This is a multiple exposure photograph of a bouncing ball. It was taken in complete darkness with the camera shutter open while a high-speed flashing light, called a stroboscope or strobe, flashed 30 times a second. Each flash produced an image.

Here’s what you can learn from this photo: The ball is moving fastest where the images are farthest apart and slowest where they are closest together. When the ball is falling, it speeds up. After it bounces and moves opposite the pull of gravity, it slows down at exactly the same rate as it sped up when it was falling until it stops for an instant and starts falling again. Each time it collides with the ground, some energy is lost. That’s why each bounce loses altitude. If the bounce were perfect, no energy would be lost, every bounce would be as high as the last and the ball would bounce forever.

A strobe also captures the split second when a tennis ball is struck by a racket. The collision flattens the ball, and stretches the strings and distorts the frame of the racket, all in .005 seconds. If these objects kept their distorted shapes, most of the force of the collision would be absorbed. But they are elastic—they restore themselves to their original shapes after they collide. This restoring force is transferred to the ball to change its direction and help add to the speed of the athlete’s swing. The fastest serve leaves a racket at 130 miles an hour. In a rally, a ball-racket collision changes direction of the ball so it is not as fast as a serve, maybe 70 miles per hour. Since the distance between images made by a strobe tells how fast an object is moving, strobes are part of the instruments used to measure the speed of balls from a tennis racket and a baseball pitcher.

Photo credit: C. E. Miller, MIT

Would you believe that you could throw an egg across the room without breaking it? Burn a candle underwater? Vicki Cobb's We Dare You! is a gigantic collection of irresistible, easy-to-perform science experiments, tricks, bets, and games kids can do at home with everyday household objects. Thanks to the principles of gravity, mechanics, fluids, logic, geometry, energy, and perception, kids will find countless hours of fun with the selections included in this book. If you would like to make a We Dare You Video, click here.
Vicki Cobb is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Cobb, Vicki. "A Bouncing Ball Like You've Never Seen." Nonfiction Minute, iNK
Think Tank, 5 Feb. 2018, www.nonfictionminute.org/the-nonfiction-minute/
a-bouncing-ball-like-you've-never-seen.

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The Battle Hymn of the Chicken Pox Troopers

Banging on the Ear Drum

Why You Can’t Defrost a Salad…Yet

How to Make Your Friends Think You're Super Strong

A Bouncing Ball Like You've Never Seen

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