## Bernoulli’s Principle: Lessons Made Out of Thin Air

November 25, 2012

by:  Tami O’Connor

A few weeks ago my daughter, a new fifth grade teacher, asked me to come into her school to present a hands-on science lesson.  Nothing delights me more than working with kids in a classroom.  After 16 years of teaching, it’s hard to be away from it.  At first I was unsure what I was going to bring in.  I have so many really neat activities at my disposal that it is difficult to select just one.  I finally narrowed it down to activities dealing with air pressure, which is part of their curriculum (always a plus!).

As I rummaged through the office, I unearthed my supply of funnels, flex straws, and ping pong balls and decided that Daniel Bernoulli would be my guest of honor that day.  When I started my lesson, I blew up a balloon and talked about air and its properties.  Inviting comments, I discovered that they had some very interesting background knowledge, and most of it was correct…

I then pulled out another balloon, only longer and made from plastic rather than latex.  It was actually a windtube; our eight foot long Bernoulli bag!  My first question was, how many breaths would take to inflate the wind tube?  Guesses ranged from 50 to one million.  It was, after all, a group of ten year olds…  I bunched the end and brought the bag to my mouth.  I decided to put just 5 breaths into the bag, and then after pushing all the air down to the bottom of the windtube, we estimated how many additional breaths it would take to completely fill the bag.  As it turned out, had I filled the bag the same way I started, it have would taken about 45 of my deep breaths to inflate it fully.

At this point I threw out a challenge: if anyone in the classroom could inflate the bag using their breath faster than I could I would give the entire class the rest of the day off to play outside.  Well, as you can imagine, the kids began to assemble their “dream team”.  I explained they could only select one person as my opponent.  They put forth the captain of the swim team explaining that his lung capacity was better developed than any of his classmates.  We stood back to back, and we each had a teammate holding the far end of our windtube so the spectators could track our progress.  One student in the class was selected to announce, on your mark, get set, and GO!  At that point I started faking the sound I would make if I were actually trying to inflate the bag, to fool my opponent into thinking I was working really hard.  After he had put about 6 breaths into his bag, I stood back and held my bag at arm’s length with the mouth of the tube wide open and blew a long steady stream of air into the opening of the bag.  Within seconds the entire tube was filled.  At this point all the kids in class began to giggle since the swim captain was turning red and still working relentlessly to inflate his bag.

Why did this happen?  According to Bernoulli, a fast moving column of air creates a decrease in air pressure.  Only a small percentage of the air in the bag came from my lungs.  The rest was drawn from the room.  As I increased the speed of the air I directed into the opening of the windtube, the pressure around it decreased and more air was drawn into the bag.

Ok, so now the class totally understood the concept, and it was time for the next activity.  I gave each student a flex straw, a funnel, and some clear tape.  They were instructed to attach the narrow end of the funnel to the short end of the straw using the tape.  I assured them that the funnel and straw did not need to fit snugly.  The tape connected the two pieces kept any air from escaping.

I asked the students to place their hand above the opening in the funnel, blow into the straw, and tell me what they felt.  As expected, the kids felt their breath exiting through the wide end of the funnel.

Now, with their new-found knowledge of how fast moving air creates low pressure, I asked the students to predict what would happen if they put a ping pong ball into the opening of their funnel and then blew into the straw.  Each and every one of them predicted that the ball would be blown out of the funnel!  Some even went so far as to boast that their ping pong ball would hit the ceiling (of course they stipulated that they had to be standing rather than sitting at their desks). Many times in my teaching career I wished I had brought a camera into my classroom.  That day was one of them!  When I counted to three, every face in the room turned red while they tried with all their might to blow that ping pong ball out of the funnel.

Of course, the ping pong ball wasn’t going anywhere.  Bernoulli’s Theorem, also known as Bernoulli’s Principle, states that an increase in the speed of moving air (or any flowing fluid) is accompanied by a decrease in the air or fluid’s pressure.  The airflow around a ball or other curved object placed in an airstream will increase its speed.  When the air increases its speed its pressure decreases.  The low air pressure created around the ball allows the high pressure from above the ball to push the ball back into the funnel.

Ok, so after the students were able to explain this concept to me we moved onto the next activity.  Using the same straw, I gave them each two pieces of 1.5”x1.5” oak tag and a toothpick.  One piece of oak tag was hole punched in the middle, and I instructed the students to attach the card to the short end of the straw so that the hole was flush with the end of the straw and it looked like a tabletop. I asked them to secure the bottom of the card to the straw using tape.

Next, I pushed a toothpick through the center of the second card and placed the two cards together with the toothpick protruding into the straw.  The next challenge…  What would happen when I blew through the straw?   Surely, after the last two demonstrations they would get this one.  Only one lone student hypothesized that the cards would remain together.  The others insisted that the cards would fly apart, but because of the toothpick the second card would fly straight up.  How I wanted to cringe.

Needless to say, the class (well, all but one) was amazed that no matter how hard they exhaled into the straw, the cards remained together.  The only thing that was even more impressive was when I instructed the class to rotate their straws 180 degrees, while holding the second card in place, and to blow.  As they blew a steady stream of air into their straws I had them remove their hands.  Then the excitement became even more apparent as the cards still remained together!  Well, at least until they stopped blowing to try to get my attention.  By this point the kids were all able to explain that the card remained in place, defying gravity, because the decreased air pressure between the cards allowed the higher air pressure from within the room to force the cards together.

The final activity involved the straw, two ping pong balls, a 12-inch piece of kite string and some tape.  Working in pairs, the students attached one ping pong ball to each side of the string with tape.  While one student held the string with the ping pong balls hanging approximately 1 cm apart, the second student blew a steady stream of air between the two.  As they had predicted, rather than moving apart, because of Bernoulli’s Principle, the spheres actually moved together!  Phew!  Though it took a little while, the concept was finally clear in their minds.  A fast moving column of air creates a low-pressure area and draws other objects in.

As I left the classroom, the students were trying to come up with other ways to demonstrate how Bernoulli’s principle could be demonstrated.  It just doesn’t get better than that!  Once I returned to the office, I realized that, though all the materials are fairly common, they not always found together.  So I put a kit together, and we now produce it at EI.  Bernoulli’s Principle Class Kit has all the materials you will need to conduct the activities mentioned above with a class of 25 students.

## CSI on a Shoestring

September 25, 2012

by:  Michelle Bertke

Would you love to teach forensics and crime scene investigation but cannot afford the kits offered?  Don’t worry!  Many products at Educational Innovations can be used together to make your own CSI kit and crime scene examination at an affordable price.

Fingerprints

One of the most common tasks of a crime scene investigator is to check the scene for fingerprints.  Analyzing a student’s fingerprints can be as simple as one, two, three!  One, collect an ink pad, a balloon, and a willing student.  Two, have the student firmly press one finger to the ink pad and then firmly press that finger onto a deflated balloon (down and up, don’t smear).  Three, blow up the balloon!

As the balloon is inflated the print will enlarge allowing you and your students to see the individual details of each finger print.  This way, you don’t need any additional materials to magnify the print, and the finer details of each fingerprint can be easily observed.

Unknown Liquids

Red cabbage indicator can be used to make an entire activity out of pH discovery.  You will need the following materials: Red cabbage indicator, test tubes/small containers, and various solutions.  That is it!  For the highest impact, a set of solutions with a wide range of pHs is best.  These could be (from lowest to highest pH) vinegar, Sprite, water, soap, and baking soda.  It is also best to use solutions that are all semi-clear if you are doing an unknown identification experiment.   First, have students use the red cabbage indicator to determine the approximate pHs of known solutions.  It is also good to have them make other observations about the solutions before they add the indicator, ie: are there bubbles, is it cloudy?.  For an extension on this concept, give the students an unknown solution and have them determine, though observation and pH, what that solution is.

Unknown Fabrics

In addition to samples of unknown liquids, Educational Innovations also has samples of unknown fabric swatches available.  By using individual samples of the fabric, a wonderful comparison experiment can be set up.  One way is to cut up and string together all the unknown white fabrics that you purchase.  Then dye those fabric swatches with cool-aid, grape juice, or red food coloring; actually anything that will make a nice color.  Now students have a series of known fabric swatches to compare to their unknown sample.  Pass out the remainder of the unknown white swatches to the students and have them make observations, just as with the liquids, about the feel and look of each fabric.  Next, have them dye their fabrics with each of the dyes used previously.  This will allow your students to carry out the process of testing and observation.

No matter what your budget, you can carry out a great CSI activity!

## Energize Your Class With The Energy Ball

August 1, 2012

by: Janice VanCleave

As a teacher, I enjoyed having people visit my class. It brought out the “ham” in me and I did and said things that even surprised me.  Rubbing a balloon on my hair and making my hair stand on ends was not unusual, but climbing on top of my desk sticking the charged balloon to the ceiling was a bit over the top.

What I disliked was the unscheduled visitor with an evaluation sheet in hand. But, I was always prepared. In fact, I had a box filled with materials for fun engaging activites. It was my “Emergency Experiment  Box.” When the evaluator unexpectedly arrived, out came the box and the show began.

My teaching abilities were being evaluated during an unexpected visit,  so I was prepared to show all my best qualities. I suggest you have an Emergency Experiment Box, and I do recommend including the  Energy Ball.

Whatever you put in your box, make sure you know as much about the experiment as possible. The Energy Ball is great for teaching the scientific method. Too often kids memorize the steps of the scientific method, but do not use them on a daily bases. The scientific method is a set of problem solving tools—but every problem does not require using every instrument in the tool box.

I regress, let me get back to using the Energy Ball to fire up your students with or without unexpected guests.

Research: Collecting information.

Use the Energy Ball to show students that research is any method used to collect information.

1. Demonstrate “Turning On” the Energy Ball by touching the metal terminals on the outside of the ball with your  thumb and forefinger of one hand. The ball flashes a red light and buzzes.

You might receive a positive note on your evaluation about your WOW! Factor.

2. Show the metal strips on the ball and explain that to “Turn On” the ball, something has to bridge the gap between the metal strips. This something has to allow electric energy to flow through it. Point out that things that allow electric energy to flow them are called conductors. Things that do not allow electric current to flow through them are called insulators.

Question: What can be used to bridge the gap between the metal strips and close the electric circuit?

Hypotheses:

You want the kids to do more than provide a list of conductors.  Instead, guide them so they learn to express hypotheses. No, hypotheses are not always needed, but they do encourage kids to pull facts from past experiences in order to make informed predictions.

Remind students that a hypothesis is what they think the answer to the question is. It is not a wild guess, but an idea based on what they already know about the Energy Ball. Give an example hypothesis, such as:

If the human body is a conductor, then a long chain of people might be used to bridge the gap, closing the circuit.

Encourage kids to volunteer hypotheses by giving them clues.  Ask, “What other things conduct electricity?” or ” What material could close the gap between the metal strips so electric energy flows?”

You have primed the kids and they should be ready to make you proud with their incredible hypotheses.

Of course, you can always count on at least one student to give an answer received from some space ship.  Don’t let this throw you off track. Keep that smile on your face, and applaud such an innovative idea.  Explain that you want to test  each hypothesis, but at this time you don’t have metal samples from their intergalactic space ship.

Quickly ask a student you can depend on for another hypothesis.  With the supplies from your emergency box the hypothesis can be tested on the spot. YEA!!  The evaluator will be thrilled that you are so prepared.

Now is the time to really engage the students as well as the evaluator.  Test your original hypothesis:

If the human body is a conductor, then a long chain of people should be used to bridge the gap, closing the circuit.

With you and your students holding hands in a circle, break the circle and invite your visitor to join in.
Ask the student next to you to touch one of the  terminals on the Energy Ball while you touch the other terminal. There is a gap between you and the visitor.

This is an example of an open circuit. Ask what needs to be done to complete the circuit. The answer will be for you to hold hands with the visitor. But that would be too simple.

Seize the moment. Have some fun and ask if a connection could be made if you touched the visitor’s nose with your finger. Of course it would. But then suggest the visitor touch your nose or your ear. If it doesn’t work, first asks if your little scamps are connected. Kids like to have a bit of fun with the teacher. Also, dry skin can inhibit the flow of electric energy. Moisten your finger with a damp paper towel (of course you have the paper towel and water bottle in your box) before touching the terminal on the ball.  The buzzer buzzes and the red light flashes. YEA!!

All lessons need closure. So, let me close by concluding that the list of steps for the scientific method are things that we do naturally when solving problems. In this activity, information about the Energy Ball was collected, questions asked, hypotheses formed, and discoveries about closed and open circuits as well as conductors were made. Yes, The Energy Ball provides opportunities to learn a lot about science. But, one of its most important values is that you and your students can use it to play and have fun with science.

Janice’s Science Challenge

I wonder…  How many people can be in the chain used to Turn On the Energy Ball?  From now until October 1, 2012, Janice VanCleave and Educational Innovations will hold a contest.  The winners will win an autographed copy of Janice VanCleave’s Energy For Every Kid and a \$25 gift certificate to Educational Innovations!

Find out specifics for entering Janice’s Science Challenge.

For more information about open and closed electric circuits, see Open and Closed Series Circuits.

If you’re interested, here’s another blog post on the Energy Ball with useful lesson ideas.

## Lights, Camera, Action!

July 21, 2012

by: Bruce Yeany

Micro LEDs and Motion

The tiny LED lights  known as Rave lights have become popular with students at dances and parties.   With the  lights turned down, kids have these lights on their hands or in gloves, and the results are totally awesome when they wave their hands around,.  Watching this phenomenon takes me back to the era of the disco ball and laser light shows.  It became apparent to me that these little lights would be fantastic when incorporated into the study of motion. Using these lights and a digital camera, it would be fairly easy to record the motion of moving objects for closer study.  Rolling, spinning , swinging, falling, projectile motion, etc. can all be captured using a camera and these little lights.

Can you figure out how these were done?

Here are some pictures I have taken over the past year.  Almost all were taken using these small lights.  In some cases the shutter was only open for a fraction of a second and in others it may have been open for several seconds.  Many of the following pictures were made using a laser pointer.

This picture depicts fire being thrown by a small trebuchet.

And of course, it’s also fun to try and write messages….. one small problem is that they appear backwards to the camera.

Bruce Yeany has been teaching physical science in the Annville-Cleona School district for the last 35 years.  He enjoys working with students and  building materials for his classroom.  Over the years he designed several  pieces of classroom science equipment that are produced and sold commercially including the World’s Simplest Motor and the Fountain Connection.   Bruce is also an amateur photographer as is his wife, Mary.  As the middle school yearbook adviser, he is quite used to having a camera around his classroom.  By combining his  hobby in photography and looking for new ways to demonstrate the motion of objects, Bruce has found that using small LED lights and a digital camera can help him freeze the movement of motion and turn it into works of art.

## Learning by Degrees: Demonstrating How Temperature Affects Expansion

July 14, 2012

by: Jonathan Smith

I’m a big fan of applied science.  Whenever possible, I like my labs and demos in my Physical Science classes to be as “real-life” as I can make them.  One rich area for science application is the topic of thermal expansion of solids.  Once students understand the underlying principles of why solids expand as they warm, I can choose from a plethora of great examples to teach the concept.

Over the years I have put together a walk-around laboratory experience where students can see the concept of thermal expansion of solids in action.  Of course I have the standard bi-metallic strip and ball and ring demos, but I also include thermostats, a taken apart toaster, and my absolute favorite, the Large Scale Thermal Expansion Apparatus from Educational Innovations.

This demonstration dramatically shows the effect of temperature change on standard household plumbing. The apparatus comes as a set of 4 segments of plastic pipe with easy twist-connectors.  One end of the apparatus fits a standard plastic funnel; the other has a downward turned drain spout.  One of the segments has a “foot” attached to it, which allows the funnel end to be firmly clamped to a table or counter top.  The position of the pipe is then marked at one end with an “O”-ring and a mark on a piece of paper is placed beneath it.  A bucket is placed beneath the drain spout. Students then pour hot water (from tea kettle on a burner) into the funnel at one end of the pipe, which then slowly drains out of the other.   As the water heats the pipe, the pipe expands.  This expansion can easily be measured by comparing the location of the “O”-ring on the pipe with the mark on the paper below it.  My students are always amazed at how much the pipe actually expands.  Running cold water through will, of course, decrease the length of the pipe.

After my students have observed this demo, I like to have them think about the everyday problems this phenomenon may cause, such as creaking or broken pipes.  I also bring to their attention some of the common solutions to these problems, such as expansion joints, specialized piping that allows for expansion and contraction without allowing a pipe to lengthen, and saddle joints, specialized holders for plumbing that allow for the expansion and contraction of the pipe.

Last year I revisited this demo and decided to try and make it even more “user-friendly”.   Instead of the funnel, I connected the funnel end of the pipe to some plastic hosing that I then connected to a faucet from a sink in my room.  I used hose clamps and a laboratory faucet aspirator to make it all work.  As it happened, the drain end of the apparatus now ends nicely at the other end of my counter right over another sink!  Students can now simply run hot or cold water from the sink and watch the expansion.  Even without the other sink as a drain, it would have been easy enough to put a bucket on that end.

A friend of mine who works at a local university and is engaged in the STEM initiative periodically visits elementary schools with basic science apparatus.  He tries to bring in materials that elementary teachers would normally not have access to but demonstrates science content that is age appropriate.  He thought that the basic concept of thermal expansion of solids was a good fit for just such lesson.  We used my modified version of the thermal expansion pipe and were quite successful.  Not only did the students understand the basic concept being taught, but the change in the length pipe was so dramatic they showed complete engagement.

## Students Dig Archeology and Paleontology

June 26, 2012

by:  Norman Barstow

Simulated Fossil Dig

Archeology is the study of society through the discovery, recovery and analysis of the material culture and environmental data that humans have left behind. The data can include artifacts, architecture, and cultural landscapes. Paleontology is the scientific study of prehistoric life.  It includes the study of fossils to determine organisms’ evolution and interactions with each other and their environments.  Most readers will recognize fictionalized accounts of the action and adventures in the pursuit of archeological or paleontological discovery from such blockbuster films as ‘Indiana Jones’ or ‘Jurassic Park’.  While this exercise may not feature the nonstop action and Hollywood fanfare of those films, it is still a fun and valuable classroom activity, not to mention much less expensive.

Objectives

The student will:

• Practice fossil preparation skills using real tools and techniques by removing real fossils from an artificial matrix.
• Be able to explain the difference between a chunk (broken piece) of fossil and a complete fossil bone.
• Be able to list reasons why broken fossils are more common in nature than complete fossils.

Materials

* Plastic butter tubs (1 per student) OR larger plastic trays (for a student group).

* Sand (use contractor or play sand, clean, with no pebbles)

* Potting soil (to add to matrix mixture and to cover the completed matrix).

* Plaster

* Water (sink)

* Bucket

* Stirring stick

* Small rocks and pebbles (per tub/tray) to add reality to the scene.

* Dental picks (w/erasers on one end, 1 per student) or dental picks with handles **

* Plastic knife

* Toothbrush or other stiff brush. (1 per student)

* Plastic trays (1 per student)

* Ziploc bags (1 per student)

* Permanent markers (1 or more)

* Pith helmet (optional)

**  Available from the Widget Supply Company

Set-up / Preparation

At least 24 hours prior to the class (but not more than 2 to 3 days prior), create one ‘fossil jacket’ per student, or group of students.

1. Set out plastic tubs on a flat surface that can be easily cleaned, such as a counter in your classroom, or outside on the grass, near your sink, water source or hose. Have your rocks and fossils nearby and easily accessible.
1. Combine 2 parts sand and 1 part potting soil to 1 part plaster (a plastic cup is a good part measure) This makes enough in a batch that won’t dry too quickly, but can be used before it dries out too much.
1. Stir dry ingredients together with stick. Add water and stir until consistency is thick but not runny, but also not dry.
1. Spread the sand/plaster mixture into a tub and smooth it out. Place the fossils in the matrix/mixture. Cover with more of the sand/plaster mixture. Repeat for each tub until finished. You will likely have to mix several batches of sand/plaster mixture to finish all tubs.
1. Stick some larger rocks on the top layer and cover with dirt. (optional)
1. Leave to dry in a dry place overnight.

(You may want to experiment with this process well before the class date so that you can judge the consistency you will need to make the sand/plaster mixture and the amount of time and materials necessary for your group. Also, the longer the jackets dry, the harder they become. Plan accordingly for the age of your group.)

Activity

1. Explain to the students that they will be acting as paleontologists, excavating a fossil site and performing the job of a preparator – cleaning fossils for identification.
1. Show students the tools that they will be using. Discuss proper and improper use of tools.
1. The students are now ready to excavate. Pass out a dental pick, toothbrush, plastic knife, and tray to each student, or use a larger tray for a group of students. (It is helpful to have extra hands for this step.)
1. Begin the preparation. The most realistic model of prepping would be to cut the sides of the tub down to the level of the matrix and just work from the top down, exposing more surface area as you go. However, if you don’t want to cut the tubs or work from the tubs, you can have the students carefully remove the entire contents (making sure the matrix remains whole) and then work from the top down.
1. For older students, you can prepare for them or help them prepare a grid, using small nails for posts, and string to mark the areas to be explored.
1. Monitoring progress: remind students about proper technique. Remind students that they are not to ‘stab’ at the fossils. Also, watch to make sure students don’t ‘stab’ their hands as they are holding the jacket, making sure to always point or press the sharp end of the tool away from their hand.
1. Soon, someone will make a discovery. Hand out Ziploc bags (1 per student) and write each student’s name on his/her bag. They can keep their finds in the bag and clean and identify them later. As discoveries occur, talk to students about what they found. Is it a rock? Is it part of an animal or flower? Why do you think that and how can you tell? Make sure that each student will be able to explain to their parents what they have found and how they are different.
1. As faster students finish you can assign them jobs to help clean up or ask them to help others who need assistance.
1. Anyone not finished at the end of the allotted time can take what they have leftover home in their bag.
1. Later, have students identify their cleaned and sorted fossils by comparing them to the Sorting Guide which is included in the Fossil Sorting Kit.

## The Science of Sound

June 9, 2012

by:  Michelle Bertke

Sound can be a difficult concept to portray because the sound waves cannot be seen or touched.  Luckily, there are several at home experiments that demonstrate the properties of sound waves.

Water tank

You can use a fish tank half filled with water to give a visual demonstration of ‘sound’ waves.  Water is a perfect medium to show the propagation of waves. This demonstrates how sound waves travel though the air.  There are two ways to display this activity.  One way is to simply press your hands onto the top of the water and allow the waves to be made by the pressure of your hand.  This allows students to see how waves travel though a medium.  You can also use this to point out the aspects of a wave such as frequency and amplitude.  Another way to show waves is to place a speaker next to the tank and allow the sound to produce the waves.  This can show that sound is a form of pressure just like your hand.

Sound tubes

Sound tubes can demonstrate how your vocal cords produce sound.  Spinning the sound tubes around in front of your body or over your head creates low or high pitched sounds depending upon how fast you spin them.  The sound is produced by air moving over the grooves in the tube.  This principle is the same as the air passing from your lungs, though your throat, and out through your mouth that creates the sounds other people hear.

Make your own record player

Another great example of how vibrations can create sound is the record player.  Record players have diamond tipped needles that fit in the grove of a vinyl record.  As the record spins and the needle passes through the grove, the cone shaped needle vibrates and the sound is amplified   These vibrations are transmitted to your ear and relayed to your brain.  Your brain translates them to sounds that you understand.  Below is how to make your own record player:

1.     Form a cone shape out of a simple white piece of paper.  Tape the bottom.

2.     Poke a straight pin about an inch from the bottom of the cone so that it crosses from one side of the cone to the other.  Position the pin so that it pokes all the way through the cone but there is some protruding on either side.

3.     Insert a pencil through the hole in the record.  Use the pencil point like a top to spin the record on a flat, smooth surface.   The record must spin in the correct direction or you will hear the recording backwards!

4.     Hold onto the top of the cone lightly with your thumb and forefinger.  Gently rest the pin on the record while you are spinning so that the pin runs along a groove in the record.

It may take some practice to get the spinning just right.  Remember, record players are set to spin at a particular speed so that the recording is heard correctly.  Play around with the speed.  How does it sound when you speed it up?  Slow it down?  Additionally, the pin should be lightly resting on the record.  If the pressure is too hard, you will just hear scratching.  If the pressure is too light, you will have a hard time hearing the recording.  (only use records that you don’t mind ruining)  This activity may take some time to get perfect but trust me, it works great!