Vicki Cobb

The "Julia Child" of Kids' Hands-On Science

     You can make the bank at the side of a waterfall appear to rise upward in the opposite direction of the falling water.  It is such an amazing illusion that I think everyone should experience it.  The problem is that most of the time people are not looking at waterfalls, or there isn’t one nearby, or they don’t know HOW to look at one in order to get the illusion.
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     When I’m at a waterfall, I tell anyone near me how to get the illusion. They probably think I’m crazy, but then they do it and they’re amazed as well.  (Or at least, they seem to be.) Since you’re probably not near a waterfall right now, I decided to hike to a waterfall in the Endless Mountains of Pennsylvania to make a video so you, too, can have this amazing experience, although I’m not sure if a video is as good as the real thing.  But hey, life is about experimenting, no? 

     So when you’re done reading this, see if you can play the video below on a full screen.  Stare at an imaginary spot in the middle of the falling water for the length of the video.  Then shift your gaze right, to the rocks in the video or wait for the freeze frame of the falls, or even try looking at something that’s not moving in your room. You should see the image rising.  If you don’t, you should probably take a hike to your nearest waterfall and try again.

     The receptor cells (the nerves in your eyes) that perceive motion get tired after a while if you are looking at falling water.  When you stop looking, the receptors that perceive upward motion are not tired, so they fire away.  As a result you perceive motion in the opposite direction although it’s not really happening. 

     The first person to observe this illusion was the famous German physicist Hermann von Helmholtz (1821-1894).  In 1860 was riding in a train, staring out the window at the scenery passing by. When he shifted his gaze to the inside of the railroad car, it appeared to be moving, but in a direction opposite to the view of the landscape.

     Next time you go to a waterfall, share your knowledge with other bystanders.  They may even thank you.  

This classic illusion book has some amazing tricks you make on yourself!  Discover the incredible shrinking sugar cube, make movie style sound effects, and fool grown-ups with flavorless coffee. 
Fooling your senses can blow your mind.
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Vicki 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.
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​Tomorrow Andrea Warren will introduce you to 11-year old Billy who went to work as a trapper, trail guide, scout, and marksman in order to support his mother and six siblings.  Can you guess the name by which we know him today?

Vicki Cobb

The “Julia Child” 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.
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Tomorrow is Earth Day and Stephen Swinburne is going to encourage you to look up and down and all around you and really appreciate our planet.

​     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.  

     In October, 1891, 23-year-old Manya Sklowdowska arrived in Paris to attend the Sorbonne, France’s great university.  She had saved money, working as a governess to get there.  She was determined to make the most of her studies in science and math.  Right away she was noticed partly because she was Polish, although she had changed her first name to a French version, Marie, to fit in better. She always sat in the front row of all her classes because her French was not yet fluent and she didn’t want to miss anything. She also was one of only a few female students. In a university full of smart people, she worked hard to excel. She ultimately finished first in her class and went on to make major scientific discoveries.  

     What made Marie so single-minded and determined?  Behind it all was a great love for science, a love she shared with her husband, Pierre Curie, whom she met in 1894. At that time, science was uncovering unimaginable truths in chemistry and physics. New discoveries were being made at a breath-taking pace.  Science was like a game and it attracted many players.  Why?

     1.       There was a Nobel Prize for winners, those who discovered a big idea about the natural world.  There was only one nature to discover but people came at it from many directions.

     2.       It was collaborative—scientists shared their discoveries by publishing papers.

     3.       It was competitive—the papers described procedures so that scientists could check each other’s work.  It kept everyone honest. The best work got the most attention.

     4.       The discoveries could be applied to solve problems for people. X-rays, light bulbs, phonographs, photographs, movies, and telephones would not have been possible without science. 

     5.       The biggest prize was the idea of the atom and its structure.  Many scientists contributed to modern atomic theory, including Marie.

     Marie Curie won the Nobel Prize twice for her work. At a time when women didn't even have the right to vote, she was a working mother of two daughters, a single mother after she was widowed in 1906, the founder of the Radium Institute for research and she brought the x-ray to the battlefield in WWI.  She believed that science could save the world, that scientific discoveries belonged to everyone. And she refused to benefit financially from her discoveries.  She lived by the highest principles of honesty and integrity.  She was a true champion of the science game.

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DK Biography: Marie Curie tells the story of the discoverer of radium, from her childhood in Warsaw, to her experiments with radioactivity in Paris, to her recognition as one of the preeminent scientists of her time.
    Filled with archival photographs and amazing fact boxes, this biography paints Marie Curie as the brave and brilliant scientist that she was.

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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.
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Tomorrow Amy Nathan is going to tell you about Sarah Key Evans, a young African American private in the US Army, who was arrested for refusing to give up her seat on a bus -- three years