Monday, January 17, 2011

Science of Sound

Every week, Madison (my 10-year old daughter) and I teach a 1.5-hour afterschool science club for K-2nd graders.  Each week she helps plan the lesson and then write the blog about what we did. 

We have provided links to the books we used to sneak in some literacy.  We learned most of the science experiments and activities from Steve Spangler (awesome speaker and science guy extraordinaire).  We have included links to his science supplies, experiments, and videos.  We have also included links to our YouTube videos. These links take you away from the blog and to external websites.

Lesson 12
Science of Sound
Science Standards Addressed:
  • Identify human organs and their function (ear).
  • Observe that things move in different ways (vibrations).
  • Observe that sound is made from vibrating objects and describe its pitch and loudness.
  • Knows that sound travels in waves.

Plus we snuck in some speaking and listening standards like asking questions, expressing ideas, following multi-step directions, and participating in discussions.

5 minutes
As the children arrived we played the songs Good Vibrations, and Catch a Wave, by the Beach Boys – little hint about the theme of the day.

Next we had a snack that once again was a hint of the science to follow. 
In addition to the healthy stuff, we could all choose between
 or the Noisiest Snack Ever Invented – POP ROCKS!

10 Minutes
To sneak in some literacy standards, while we ate snack Madison read them 
Moses Goes to a Concert, by Isaac Millman.
Moses is deaf so is all of his class. They go the concert where they meet the percussionist who is also deaf.  Moses and his class learn how to feel the music by holding balloons in their laps. The balloons help them feel the vibrations of the music. When Moses went home he told his mom that when he grows up he wants to be a percussionist. In the book there was lots of sign language which made the book interesting.

After the book, we just chatted about sound and asked what they already knew: Can sound travel in water? What do things sound like under water? Can sound travel through solids? Can we always see things that are there? What happens to sound when it reaches a wall or other solid, flat object? Why does a tile floor sound louder than a carpeted floor? Does sound travel better through solids or air?  Then we tested that one out by putting our heads on the table and knocking.

5 Minutes

Singing Rod

Link to Singing Rod

To get them really excited and engage their emotions, we started with some cool demos! For the singing rod, I put a little rosin on my fingers, gripped the Singing Rod tightly at the midpoint and rubbed the Singing Rod between my thumb and fingers from its midpoint to the end. In a couple of seconds, she really began to sing.

LOUD! And with each continued stroke it got louder and louder.  You should have seen the kids faces!  WOW!  Most of them screamed back and held their ears!
 We talked about the rosin and how it is used to make bows stick and slide across the strings of stringed instruments and how baseball pitchers use rosin to make their pitching hand sticky so they can give the ball a strategic spin when they pitch.  When my fingers stick and slide across the rod it creates vibrations – good vibrations.

We explained that sound is a type of energy made when an object vibrates - causing movement in the air particles. These particles bump into the particles close to them, which makes them vibrate too causing them to bump into more air particles. This movement, called sound waves, keeps going until they run out of energy. If your ear is within range of the vibrations, you hear the sound.
We explained (very simply) what happens in the ear using a giant ear model.  The sound waves are funneled into your ear by your outer ear.
When the sound waves reach your eardrum, they make it vibrate –
which vibrates three tiny bones.
  These bones make fluid inside of this little thing shaped like a snail vibrate, which vibrates little hairs.  These vibrations are detected
and transmitted by a nerve to the brain.

15 Minutes

Tuning Forks 

Link to Tuning Forks

We showed them how tuning forks vibrate to produce sound.

As the tines of the tuning fork vibrate they strike air molecules, which bump into neighboring molecules, creating a crowded wave (compression) of molecules followed by an “anti-wave” with fewer air molecules – and then another compression wave and so on. 
It is very much like throwing a stone into a pool of water – waves radiate out indefinitely from that spot.

After striking the tuning fork, we dipped it in water to show the kids how the vibrating tines splash the water.  Wow factor!

Then we let the kids have some time to explore tuning forks independently. 

15 Minutes
Slinky Science
We used a Slinky toy to show them what compression waves look like.
We stretched it out on the floor and one of the kids held it on each end.  Then one kid would push his end of the slinky towards the other kid and bring it back – creating a compression wave that travels to the other end and back again.  It is pretty cool.
If you graph the compression wave using an old oscillograph or see it represented digitally on an oscilloscope you can see a transverse wave.

When the vibrations are fast, you see a short wavelength, and you hear a high note.
When the vibrations are slow, you see a longer wavelength - a low note.
  Higher amplitude means higher volume.
We showed them what a transverse wave looks like by moving the Slinky from side to side,
creating nodes and antinodes.
Then we tied a 4-foot piece of string to each Slinky so that there was a
2-foot length on either side of the knot

We held the string in each hand

and pressed the string into our ears with our fingers. 
Then just knocked the Slinky around and listened.  You’ve gotta try this. You’ll be amazed. The odds are high that someone will say the words “STAR WARS” because it sounds just like the space gun sound effect!

15 Minutes
Whirly Tubes

We got a bunch of these Whirly Tubes. 

Before letting the kids get their hands on them, we asked them to imaging that a tube was filled with marbles.  We asked what would happen if we then twirled this tube full of marbles around above our heads.  “They would go everywhere!”  Right!  Now imagine the tube is filled with air molecules.  What would happen if we twirled it?  Right – we fling air molecules out of the tube and more air pours right in from the open end.  As the air molecules travel across the bumps of the corrugated tubes it causes bounce against each other and vibrate – and that causes a fun sound.
We gave children whirly tubes, asked them to spread way out and turned them loose!
When we whirled the tubes faster, the pitch of the sound went up. Fast whirling created high pitch notes and slower whirling created lower notes.

10 Minutes
Screaming Balloons-

Link to Screaming Balloons
This activity is kind of like that motorcycle rider in the metal sphere at the circus. We took a clear plastic balloon, put a hex nut inside, inflated the balloon, tied it off, and began what Steve calls the MOST ANNOYING SCIENCE EXPERIMENT EVER. We just held the balloons in our hands and began a spinning-swirling motion. Thanks to the inertia supplied by our hands and the centripetal force of the balloon, the nut flips up on its edge and spins around the inside the balloon – vibrating to making a fun (annoying) sound. Centripetal force is the inward-seeking force that causes the nut to go in a circular motion. The gravity of the sun is the centripetal force that keeps our planet going in a circular motion. Good thing – if it weren’t for that force, we’d go flinging off into space.

15 Minutes
Pop Rocks Science

To end the day we did a just-for-fun prepackaged “experiment” with Pop Rocks, the NOISIEST candy ever!

First we filled a small test tube (included) half way with water. Then we added some Pop Rocks and listened to the popping sounds.

According the manufacturer sugar and flavors are boiled and mixed with carbon dioxide gas under pressure. The process causes tiny high-pressure bubbles of carbon dioxide gas to form in the candy. When you pop some in your mouth, the candy melts and the bubbles of gas are released with a POP. Very cool!

Then we added secret ingredient #1 (I think food coloring and citric acid).  This turned the mixture blue.
Then we added secret ingredient #2 (I think crystalline powder of Sodium Bicarbonate – AKA; Baking Soda).
This created an awesome bubbling, oozing, concoction! A fun way to end the day!

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