The Old Dog and the New Tricks

May 15, 2013

Crawford jpegby:  Ken Crawford

An amazing thing happened to me about 18 months ago…I learned something new!  Now, I know that might not seem like a major thing…but for a person who has been a social studies teacher and administrator for 30 + years…I sometimes think that I have seen it all…nothing much new out there…but a single phone call changed all of that.

I received a call from a friend asking if I would be willing to meet with a gentleman who had invented a new teaching “tool”.  He wanted to know if it would help teachers to be more effective in their classrooms.  More effective teaching is something that I am always interested in…so I agreed to meet.

What I had a chance to see was a teaching tool called the PowerWheel. A micro hydro generator, it had the capability of using water from a sink to create enough electricity to light up a string of LED lights, charge up a cell phone or even power up a notepad.grn200_3 grn200_2

Roy Bentley, the inventor/designer, asked me if I thought it might be something that teachers could use to help them teach students about energy.  I remember telling him, “I’m a social studies teacher…we need to ask some science teachers”. I put together a focus group of teachers that represented grade levels from 3rd grade through college.  Some taught science all day long, others were expected to include science as part of their overall curriculum. We gathered them together in a room and just let them “play” with the PowerWheel.  We had a great time, received some great feedback and saw what fantastic teaching ideas can be generated by a group of enthusiastic educators! I think I learned more about science in one day than I had in the past 20 years….it was amazing!

And for me, it was an eye opener.  Science hadn’t been my strength in school, but here was a tool that was easy to use, easy to understand and even had me thinking about how I could use it in a classroom. The old dog was learning new tricks!

The PowerWheel has really taken off.  It has been featured in a number of websites (including here at Educational Innovations) as well as been the hit of a number of conventions and gatherings of science teachers.  Over the next few months, I look forward to sharing some great lessons on energy, and provide some great examples of how the PowerWheel is being used by other educators throughout the country. Stay tuned!

Ken Crawford first began teaching in 1975.  He has been a teacher, coach and administrator at the junior high, high school and post-secondary levels.  He continues to teach at the community college and university levels including supervision of student teachers interested in entering the profession. He also serves as the Director of Marketing and Learning Resources for RB Manufacturing-the producer of the PowerWheel

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Posted by Tami O'Connor

Magdeburg Vacuum Plates

April 1, 2013

Jon Smityby: Jon Smith

Teaching the basic concepts of air pressure has always been one of my favorite units in Physical Science.  There are so many great demonstrations, some with long colorful histories.  One classic standby is the use of the famed Magdeburg Hemispheres.  The Magdeburg Hemisphere demonstration was invented in 1656 by Otto von Guericke, then mayor of Magdeburg, Germany.Magdeburg1

Having just invented the world’s first vacuum pump, Von Guericke set to work creating a device to demonstrate its valuable contribution to science.  That device was the Magdeburg Hemispheres.  Von Guericke’s original spheres were much larger than those commonly available today and made of thick metal.  He used them to dramatically demonstrate the pressure of the atmosphere by evacuating them and using two teams of 15 horses to attempt and pull them apart.  Of course the horses failed to separate them.

Most spheres commonly sold today are made of cheap black plastic and meant to be evacuated with a typical classroom vacuum pump.  They do a reasonable job of demonstrating the basic concept, but, in my own experience, do not hold up well to normal classroom use.  Over the span of my 20 year career I have probably had to replace these hemispheres at least five times.

vac200When Educational Innovations began selling their Magdeburg Vacuum Plates, I thought that I would give them a try.  I was incredibly impressed!

While the plates lack the traditional hemispheric shape, what is gained from the shape change is significant.

By changing the area exposed to atmospheric pressure to a two dimensional circular surface, my 9th graders had no problem calculating the exact amount of pressure holding the plates together.  In addition, because the plates are two dimensional it allowed the designer to provide three different sized grooves and “O”-rings to actually change this area.  When the area is decreased, the force that holds the plates together is also decreased.  Not only can my students do the calculations to determine the new areas and corresponding forces, but they can “feel” them as well.  Using the largest groove and “O”-ring creates an area that requires roughly 170 lbs of force to separate.  Using the smallest “O”-ring, it only takes little over 60 lbs.

vac200_2The product also comes with a very nice manual with a suggestion that I had never thought of.  Once I have my students calculate the force required for a given area, I have one student stand on a bathroom scale holding the upper handle of the evacuated plates while another student sits on the floor in front of the first student and pulls downward on the lower handle.  The students then watch the scale and note the maximum weight it records before the plates separate.  This weight, subtracted from the student’s weight, roughly approximates their calculated force.Mag.2

I particularly like the fact that the vacuum plates come with their own hand pump.  While I own both a classic large laboratory electrical vacuum pump and a smaller “squeeze-type” pump, I love the fact that the included pump has an obvious mechanism that students can see.  The creation of the vacuum between the plates becomes something transparent and understandable rather than a magic “black box.”   This same pumping system is used in Educational Innovations’ mini-bell jars, and I love those, too.vac10

Finally, I am most impressed with the strength and durability of these plates.  My set has been dropped, kicked, and beaten in every way imaginable by 9th graders over the past 5 years, and they still work like they did the day I took them out of the box.  I used to guard my Magdeburg Hemispheres protectively.  Now I pass these plates around the room and just let my students “have at them.”  It’s nice to have the kind of durability that turns a quick “one-off” demo into a truly “hands-on” experience.  Thank you EI!

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Posted by Tami O'Connor

Missile-aneous Scientific Principles

March 4, 2013

tamiby: Tami O’Connor

One of the things I enjoy most about my job at Educational Innovations is conducting teacher workshops.  It’s not quite the same as being in the classroom in front of twenty-plus students, but it’s fun nonetheless.  My favorite presentation is titled, 3-2-1 Blastoff!  In it, we deal with energy, forces, and motion.  I use the Mighty Missile Launcher to demonstrate these topics.

It is exactly that…  a missile launcher.  The good news is this missile launcher can be used safely in a classroom with children from kindergarten to college level. Participants need safety glasses or goggles.

The launcher is primarily constructed of a film canister, a straw, and a balloon. The balloon has a sponge-like material inside that functions to re-inflate the balloon quickly.  The balloon is attached to the film canister so little air is able to escape.  The film canister pivots, allowing you to aim it at differing angles.  The four missiles are simply straws, sealed on one end, with foam fins that stabilize them as they fly through the air.photo

I first demonstrate how the missile is launched.  The missile is loaded onto the launcher by sliding it onto the straw that is slightly less narrow than the missile.  Since the balloon is connected to the film canister, air can flow easily between the two.  Depressing the balloon forces air into the film canister and out through the attached straw.  When a missile is loaded onto the straw, the forced air propels it into the air.  The harder and more quickly the balloon is squeezed, the faster the air flows into the missile.rkt600

Next, I make groups of three or four individuals, and I challenge my teachers to consistently land three out of four missiles inside a target area 1 meter away.  Seems like a cinch, right?  Not so fast…  As with every good science activity, there are several variables that must be controlled.  The first is the force at which the missile is launched.  The harder and faster the balloon is squeezed, the faster the air is compressed and the farther the missile travels.  The second is the angle at which the film canister points.  The greater the angle, the higher and shorter (in horizontal distance) the missile travels.photo copy 2

So, the question is, how can we control these variables?  In my workshop, I provide rulers and protractors.  The participants quickly learn that controlling the force is not an easy task.  Most people try to use their hands to launch the missiles, but it is difficult to apply the same force for each launch.  That’s where the ruler comes into play.  By finding an object that can be dropped onto the balloon at a constant height, participants are better able to control the amount of force applied to the balloon.photo copy 3

The protractor is used to control the angle that the turret is pointing.  The angle must be smaller if the force is less and the angle must increase if the force increases.  Participants also realize that after most launches the launcher moves.  Using some masking tape to secure the launcher to the table can control this problem.photo copy

The missile launcher most easily teaches Newton’s Laws of Motion.

Newton’s first law states that an object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.  This law is often called, “the law of inertia”.

The missile will remain on the launcher until acted on by a force.  The force that propels it is the unbalanced force of the air inside the missile pushing against the inside of the balloon. In deep space, where there is no air and little gravity, the missile, once launched, will continue on forever, unless it runs into another force (which could be an object traveling in another direction).  Here on earth, the friction from the air molecules slows the missile, and gravity pulls it downward.

According to Newton’s second law, acceleration is produced when a force acts on a mass.  The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).   This principle is also expressed using the equation F=ma

Newton’s second law, F=ma can be illustrated by the force with which you depress the balloon.  Since the mass of the missile is constant, the greater the force at which you launch it, the greater the acceleration.  The greater the acceleration, the farther the distance the missile travels.  An interesting way to take this one step further is to add some mass to each missile.  By keeping the force constant, students can see that more massive objects have less acceleration while using the same force.

Newton’s third law states that for every action force there is an equal and opposite reaction force.

As the air shoots out of the base of the missile a force is applied to the film canister and to the air behind the missile.  As a result, an opposite force is applied to the missile.  Since the missile has less mass than the launcher, the missile is propelled into the air.

This activity is a favorite of teachers and students alike.  It looks easier than it is, and, by the end of the activity, participants gain skills working in teams and experience with force and motion.

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Posted by Tami O'Connor

Film Canister Capacitors

March 1, 2013

6769_100121036671012_100000193470961_521_4265928_nby: Norm Barstow

This is a guide on how to make a Leyden Jar that makes awesome sparks with materials you may even find in your house. It’s inexpensive, basically harmless and fun.

Here is the list of materials you will need:

  • An empty film canister with lid.  These are available at Educational Innovations.
  • Multistrand insulated wire; eg. type HPN Heater Cord
  • Single conductor/solid un-insulated wire, about 1.5 mm in diameter (16 gauge copper wire).
  • Some aluminum or copper foil. (NOTE: Any conductive foil will work. Copper foil is thicker and easier to work with than aluminum foil, but aluminum foil works. Heavy duty aluminum foil works best.
  • A bolt (10/24) with a round head that is shorter than the film canister’s height. Two nuts that fit the screw.  Washer is optional.
  • Scotch tape.

photo

Now that you have all the parts, get to work.  See the diagrams below to guide you.

1.  Drill a hole or poke a hole in the lid of the film canister. The hole should be just wide enough to let the bolt fit snugly inside it.

2.  Next, cut a rectangle of foil large enough to wrap around the outside of the film canister and about 2/3 of the height of the canister.

3.  Tape the foil to the canister, being sure to leave an open section for the loop of wire that will go around the canister over the foil. (You should just need to tape the edges of the foil to the outside of the canister.) DO NOT USE Rubber cement. It is highly flammable and explosive and could be set off by sparking inside.

4.  Cut another piece of foil (same size) and fasten it to the inside of the canister. If you are using heavy duty foil, you shouldn’t have to use tape. The tension of the foil being rolled up should be enough to keep it plastered to the inside of the canister. If you use normal foil, you’ll have to tape the edges. It is very important that the foil touches the container all the way around the inside of the canister.

5.  Cut the multistrand wire: It should be about 1″ (2 cm) long and have .25″ or (.75 cm) of insulation stripped off the outside of both ends.

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6.  Next, using the bolt and nut, secure the multistrand wire to the top of the lid. Form one end of the multi strand wire in a hook shape to fit the bolt.

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7.  Fan/spread out the conductors on the other end of the multistrand wire.

8.  Secure the solid wire to the underside of the lid, making a loop at the end so that it won’t tear the foil. Then bend the wire so that it will touch the inside of the canister.

photo

9.  Place the lid on the canister, ensuring that the wire loop touches the foil on the inside. Adjust if necessary.

10.  Last, wrap a piece of the solid wire around the outside the canister, twist tight and then continue in slight curve up toward the bolt. Shape the end near the bolt into a small circle.  MAKE SURE that the top of the wire is at a MAXIMUM of ¼” away from the bolt.

11.  After the copper wire is in position, cover the wire with scotch tape or electrical tape so you don’t shock yourself while handling it.

What you’ve built is a very simple capacitor. To use it, simply wave the canister over the surface of CRT TV screen or monitor, or anything that makes static electricity (the multistrand wire ‘receives’ the static electricity and therefore must be closest to the static source.)

Capacitor

Then gently push down the end of the outside solid wire so it reaches a little closer to the bolt head, without touching  and ZAP!  There’s your spark.

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SAFETY

Most of the time, the jar will discharge itself with no extra help. Please note that the finished jar holds high voltage, low current electricity, which is normally harmless. However, don’t take any chances! If you’re not sure if it’s charged or not and you think it’s not safe. Simply press on the outside of the wire against the bolt to completely discharge it. Keep your finger away from the bolt head area as much as possible while it is charged. You don’t want an ‘accident’ (you’ll just get a static shock. No one likes getting a static shock.

If you’re having trouble charging the jar (CRT TV or monitor), follow the directions for building a Static Electricity Generator.

Static Electricty Generator with PVC Pipe

  • Materials:
  • A PVC pipe, ¾“ wide and about 3-4′ long.
  • Fur, wool, or cotton fabric.

To operate:

  1. Take the fabric and rub it along the pipe all the way up, and then all the way down.
  2. Have someone else hold the jar; pressing the multistrand pickup wires to the pipe, and then discharge the jar after a few seconds of rubbing.

Check out another great Blog on Leyden Jars.

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Posted by Tami O'Connor

Look, Mom, No Wheels!

February 25, 2013

6769_100121036671012_100000193470961_521_4265928_nby:  Norm Barstow

The first practical design of the hovercraft was completed in the late 1950′s by British engineer, Sir Christopher Cockerell.  Since then, the continued development of this invention has been ongoing, and currently, the hovercraft is being used commercially, by the military, and for personal use.  Teachers have been constructing versions of the hovercraft using balloons, film canisters and flat materials in classrooms for years.

The principle behind the hovercraft’s levitation is that when the air is released from the balloon, it hits the ground and rushes outward in all directions. The air flowing from the balloon through the holes forms a layer of air between the hovercraft and the table. This reduces the friction (the resistance that occurs when two object rub against each other) that would have existed if the hovercraft rested directly on the table. With less friction, your hovercraft scoots across the table.

Furthermore, extra air molecules are packed underneath the structure, which in turn increases the pressure under the hovercraft.  This increased pressure below the craft produces an overall upward pressure force on the craft therefore it supports its weight. Since air molecules are always leaking out from beneath the craft, you’ll need a source of air molecules to replace them, which is provided by the balloon.

Materials:hovercraft1

·      Large plastic plate (not the inflexible type)
·      Foam meat tray from grocery store  (6.5” X 8.5”)
·      Old CD
·      Stiff cardboard

  • Poster putty such as Blue Tak, or Poster Tak
  • Smooth surface
  • Hole instrument: Ball point pen tip or hot nail or drill.

Construction of the hovercraft:

1.  Find the center of your base and make a hole (3/32” or about the size of  the hole in a spool of thread.)  Caution.  If you use the plastic plate, it is best to use a hot nail because a ballpoint pen tip will not make a round hole.  Use vise grips to hold the nail and heat it over a flame.

2.  Make a similarly sized hole in the bottom of the film canister. You can use a ball point pen here or a hot nail.hovercraft2

3.  Stretch the balloon and fit the opening over the open end of the film canister.  Be sure to fit the balloon far enough onto the film canister so the neck of the balloon keeps the inflated balloon upright and does not flop over.hovercraft3

4.  Make a ring of the Poster Tak around the hole in the base. Be sure not to cover the hole.  The ring should be the diameter of the film canister base.hovercraft4

5.  Inflate the balloon by blowing through the hole in the bottom of the film canister. When it is fully inflated, have a partner pinch the neck of the balloon or twist it so it doesn’t deflate.

6.  Carefully set the balloon/film canister assembly on the ring of poster putty and press down to seal.hovercraft5

7.  Place the Hovercraft on a smooth surface and let the air flow.hovercraft6

8.  Give it a little tap to get it going.

Here is a step by step video to help you get going:

HINTS and SUGGESTIONS:

  • Place a piece of tape over the base of the hovercraft until you’re ready to launch.
  • Experiment with inflating the balloon, twisting it to seal in the air, and then trying to fit the balloon neck over the film canister opening.
  • Experiment with different hole sizes, bases, balloon sizes.

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Posted by Tami O'Connor

We Water Molecules Stick Together!

January 14, 2013

tamiby: Tami O’Connor

I am a believer that observing discrepant events burns concepts into students’ memories far longer than simply reading the facts of the lesson from a text book.  A few years ago I was designing a unit on surface tension.  Because so many awesome hands-on activities deal with this topic, my greatest problem was picking and choosing!  In this blog, I will describe one of my students’ favorites.  It teaches about surface tension and capillary action.

DSC_0277Materials (per student):

  • 2 – plastic cups (I prefer Solo brand)
  • Electrical tape
  • 18 inches of white yarn
  • Food coloring
  • Water

Procedure:

DSC_0278Cut 2 pieces of electrical tape (1 inch each).  Using the tape, affix the end of the yarn to the inside bottom of one of the cups.  With the other end of the yarn, repeat with the second cup.  Put as much yarn as will fit into one of the cups, and add water until the cup is about half full.  Holding the cups close together, pour the water from one cup to the other allowing the yarn to flow with the water.  When the yarn is thoroughly saturated you are ready to begin.

DSC_0279Hold the cup with the water directly over the empty cup and pull the yarn taunt.  Slowly pour the water from the top cup into the bottom.  You should notice that the water flows from the lip of the cup and follows the yarn into the lower cup.  Reverse the position of the cups so the full cup is now above the empty one.  Offset the top cup so it is about one inch to one side of the lower cup.  With the yarn stretched tight between the two cups and the yarn from the top cup stretching over the lip on the side of the cup closest to the bottom cup, pour the water so it flows along the yarn and into the lower cup.  If done correctly, you will notice that, even though the top cup is not directly above the bottom cup, the water does not fall straight down but rather flows diagonally along the yarn.

You will find that you can offset the cups by several inches, and, as long as the yarn is tight and along the side of the top cup that is on the same side of the lower cup, the water will continue to follow the yarn into the lower cup.

Why does this happen? 

Molecules of water form a cohesive force with one another.  This force holds the molecules of the water together, so, when the weight of the water pulls it downward because of gravity, it in turn holds onto the water around it.  Since the fibers of the yarn are saturated with water, the water leaving the cup follows the yarn downward into the lower cup.

Try This:  After students have successfully poured water from one cup to another at an angle greater than 10 degrees, have them attach dry yarn between two new cups the same way they did before, but this time, keeping the middle section of yarn dry when water is added to one of the cups. Have the students try to pour the water at a 10 degree angle again with the new cups and dry yarn.  I suggest keeping a lot of paper towels on hand!

Why does this happen?

Since the yarn does not have any water on it, the water’s weight due to gravity acts on it without the cohesive force of the additional water in the yarn; therefore it falls straight down rather than diagonally across the yarn.

Next Activity:

DSC_0282Find books, boxes, or other objects that will raise the height of one of the cups above the desk.  Using the cups with the wet yarn, place the cup containing water on top of the raised surface.  Move the empty cup at an angle lower than the top cup.  Move the cups away from each other so the yarn is pulled taunt.  Leave the cups for about 20 minutes and observe the level of the water in the two cups when you return.

Why does this happen?

Capillary action is ability of a liquid to flow in opposition to external forces like weight due to gravity. It is defined as the movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension.  Because of capillary action, paper towels absorb spills, trees and plants are able to carry water and nutrients from their roots up through the plant tissue, and forensic scientists can use chromatography to help solve crimes.

More:

Some students have difficulty believing that the water from the raised cup is, in opposition to gravity, actually traveling up the yarn to the lip of the cup and then downward along the diagonal of the yarn into the lower cup.  That’s where the food coloring comes in…  close to the surface of the water, but being careful not to get it in the water, place a drop of food coloring on the yarn inside the top cup.  As the water travels up from the cup and along the yarn it will carry the food coloring along with it.  The food coloring will travel down the yarn showing the speed at which the water is moving.  As the color leaves the lip of the cup, use a second color on the yarn just as you did the first color.  Repeat each time the previous color leaves the cup until you have a rainbow of colors traveling down the yarn!

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Posted by Tami O'Connor

Picture This!

January 10, 2013

MARTY SAGENDORFby: Martin Sagendorf

It’s Easy:

To take neat photos of little things.

We Think:

That our digital cameras, web, and cell phone cameras can only take ‘life-size’ photos… but…

We’re Lucky:

These cameras can also photograph images provided by other optical devices…

Such As:

Microscopes and spectrographs.

Because:

These devices provide collimated images (i.e. focused at infinity) and an ordinary digital camera device can photograph these images.

The Images:

Are much smaller than ‘full frame’ – a photo-handling program is an absolute necessity – to enlarge and enhance the images.  For the camera images shown, the camera used is a Panasonic DMC-TZ4.

For Example:

A slide-mounted hibiscus stem cross-section – through a 5X loupe.

This is the full image as it is captured by the camera:

PHOTO - 688 - FULL SIZE - LOW RES - EYE-242

The same image after partial cropping and enlarging:

PHOTO - 688 - PARTIAL CROP - EYE-242

And the same image after full crop and enlarging:

PHOTO - 688 - TIGHT CROP - EYE-242

Three More Photos Of The Same Slide:

Through a 30X hand-held microscope:

PHOTO - 684 - TIGHT CROP - MIC-30

Through a 30X single-eyepiece microscope:

PHOTO - 679 - TIGHT CROP - MIC-500

Through one eyepiece of a Bausch & Lomb binocular microscope @ 19.5X:

PHOTO - 685 - TIGHT CROP - B and L

And Another Slide:

A slide-mounted fish scale photographed through a 30X single-eyepiece microscope:

PHOTO - 689 - TIGHT CROP - FISH SCALE - MIC-500

The same photograph enlarged even more:

PHOTO - 689 - EXT. MAG. - FISH SCALE - MIC-500

Using A Web Cam:

Photo of a slide-mounted Aves Feather taken with an H.P. Webcam 3100 into a 30X microscope:

PHOTO - IMAGE97 - TIGHT CROP - AVES FEATHER - MIC-500

Through Spectroscopes Using A Camera:

Sunlight through a hand-held adjustable slit spectroscope:

PHOTO - 692 - TIGHT CROP - SUNLIGHT - ROY-100

An 18 Watt yellow Compact Florescent Lamp through a hand-held adjustable slit spectroscope:

PHOTO - 715 - TIGHT CROP - YELLOW CFL - SPECTRO - ROY-100

Sunlight through a hand-held spectroscope with scale:

PHOTO - 640 - SUNLIGHT - SPECTRO - SPC-100

An 18 Watt bright white Compact Florescent Lamp through a hand-held spectroscope with scale:

PHOTO - 636 WHITE CFL - SPECTRO - SPC-100

It Takes Some Patience…

To align the camera to the device being used and to find the optimum exposure (light) level.  Fortunately, using a digital camera allows one to immediately see the image and make adjustments if required.  And using a small piece of black cardstock (with a ½” hole) will act as both a light block and protection for the camera and device lenses – sometimes it’s advantageous to tape the cardstock in place.

The Images On The Photos…

Will be quite small – a photo-handling computer program must be used to enlarge and enhance the images.  Photoshop, or any of the many other image-handling routines will do this.  The images in this blog were handled with Corel Paint ® Version 8 – it provides enlargement as well as changes of contrast and other photo characteristics.

Actually Doing It:

Cardstock piece:

PHOTO - 754

Using a digital camera to photograph a slide-mounted object through a 5X loupe.  An LED flashlight illuminates the white paper under the slide.  Note that the slide is supported on two pieces of wood – this avoids a shadow of the object mounted on the slide:

PHOTO - 228

A 30X hand-held microscope and digital camera:

PHOTO - 230

Photographing through a 5X loupe with an iPhone:

PHOTO - 765

A webcam shooting into a microscope’s eyepiece:

PHOTO - 758

An iPhone taking a microscope photo:

PHOTO - 759

A digital camera taking a ‘spectro’- photo:

PHOTO - 232

And through an adjustable-slit spectroscope (note use of the cardstock piece):

PHOTO - 234

Great for…

Individual or group investigative activities incorporating actual images either as single entities or as collages.

CAUTION !

Never point any optical device towards the sun!

Remember to:

Experiment for the best results – especially light levels.

bk460Marty Sagendorf is a retired physicist and teacher; he is a firm believer in the value of hands-on experiences when learning physics.  He authored the book Physics Demonstration Apparatus.  This amazing book is available from Educational Innovations – it includes ideas and construction details for the creation and use of a wide spectrum of awe-inspiring physics demonstrations and laboratory equipment.  Included are 49 detailed sections describing hands-on apparatus illustrating mechanical, electrical, acoustical, thermal, optical, gravitational, and magnetic topics.  This book also includes sections on tips and hints, materials sources, and reproducible labels.

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Posted by Tami O'Connor

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.

1 Comment | Elementary Level, Experiments, Middle School Level, Physics | Tagged: , , , | Permalink
Posted by Tami O'Connor

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.

Leave a Comment » | Elementary Level, Energy, Experiments, Middle School Level | Tagged: , , | Permalink
Posted by Tami O'Connor

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.

Leave a Comment » | Elementary Level, High School Level, Middle School Level, Physics | Tagged: , , , , , | Permalink
Posted by Tami O'Connor

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