High School Level |

The Old Dog and the New Tricks

May 15, 2013

by: 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.

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 3^rd 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

Leave a Comment » | College Level, Elementary Level, Energy, Experiments, High School Level, Middle School Level, Physics | Tagged: Green energy, hydropower, micro hydro generator, PowerWheel, renewable energy | Permalink
Posted by Tami O'Connor

Magdeburg Vacuum Plates

April 1, 2013

by: 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.

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.

When 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 9^th 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.

The 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.

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.

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 9^th 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!

Leave a Comment » | Earth Science, Experiments, High School Level, Middle School Level, Physics | Tagged: air pressure, Hands-on activity, Magdeburg vacuum plate, science, vacuum chamber | Permalink
Posted by Tami O'Connor

Missile-aneous Scientific Principles

March 4, 2013

by: 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.

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.

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.

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.

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.

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.

1 Comment | Elementary Level, Energy, Experiments, High School Level, Middle School Level, Physics | Tagged: energy, force, inertia, missiles, motion, Newton's Frist Law, Newton's Second Law, Newton's Third Law | Permalink
Posted by Tami O'Connor

Film Canister Capacitors

March 1, 2013

by: 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.

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.

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.

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.

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.)

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.

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:

Take the fabric and rub it along the pipe all the way up, and then all the way down.
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.

Leave a Comment » | Experiments, High School Level, Middle School Level, Physics, Static Electricity | Tagged: capacitor, DIY, film canister activities, Generators, leyden jar | Permalink
Posted by Tami O'Connor

Picture This!

January 10, 2013

by: 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:

The same image after partial cropping and enlarging:

And the same image after full crop and enlarging:

Three More Photos Of The Same Slide:

Through a 30X hand-held microscope:

Through a 30X single-eyepiece microscope:

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

And Another Slide:

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

The same photograph enlarged even more:

Using A Web Cam:

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

Through Spectroscopes Using A Camera:

Sunlight through a hand-held adjustable slit spectroscope:

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

Sunlight through a hand-held spectroscope with scale:

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

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:

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:

A 30X hand-held microscope and digital camera:

Photographing through a 5X loupe with an iPhone:

A webcam shooting into a microscope’s eyepiece:

An iPhone taking a microscope photo:

A digital camera taking a ‘spectro’- photo:

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

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.

Marty 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.

Leave a Comment » | College Level, High School Level, Physics | Tagged: digital camera, iPhone pictures, magnification, photography, spectroscope | 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: Bruce Yeany, laser light show, led, light, motion, persistance of vision | Permalink
Posted by Tami O'Connor

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.

1 Comment | Elementary Level, Experiments, High School Level, Middle School Level, Physics | Tagged: large scale thermal expansion apparatus, STEM, Thermal expansion | Permalink
Posted by Tami O'Connor

Faster Than a Speeding Bubble!

April 28, 2012

by: Cindy House

Speed of the Bubble Apparatus

Bubbles in tubes offer many advantages over spheres on ramps for velocity and acceleration experiments:

The bubble stays in the tube! There are no escaped marbles to chase down.
The bubble moves more slowly than a marble, permitting more accurate determination of elapsed time.
Results are highly reproducible.
Many data points can be collected in a short period of time.

A simple apparatus to hold and protect the tube is easy to construct from scrap and/or inexpensive materials. It enables even very young students to obtain highly reproducible data quickly. It also protects the tubes from being damaged if dropped or bumped. Plans and suggested materials are included in this blog. The following experiment is one I use with the elementary students in our after school science club.

Equipment (per pair of students)

1 bubble tube (22 inches long)

1 MyChron timer

1 bubble tube apparatus

hook/loop strap (optional)

data tables

per class of 30 students: 3 each of 15^O, 30^O, 45^O, 60^O, 75^Oand 90^Oblocks.

From start to finish this experiment can be comfortably accomplished within one hour if the tubes are already installed in the apparatus. I first demonstrate how to use the apparatus, then ask the students at what angle they think the bubble will move most quickly and why. After recording their responses we start the experiment.

Procedure:

Each pair of students selects an angle block; it makes no difference which degree value is chosen first. They push the block into the axis between the swing arm and base as far as it will go, securing it with the hook/loop strap. The strap is optional, but it makes it easier for the children to hold the block in place when they’re tipping the apparatus.

One partner returns the bubble to the starting position before each trial by tipping the entire apparatus until the bubble gets to the end of the tube. She quickly, but gently, sets the apparatus base flat against the table as her partner prepares to start the timer when the front of the bubble touches the thirty centimeter line. He stops the timer when the front of the bubble touches the zero centimeter line.

They do three trials of each angle, then calculate and plot the average values using a bar or scatter chart.

Discussion:

When all teams finish collecting and analyzing their data, we compare and discuss the results. The student teams found that either 45^Oor 60^Oproduced the speediest bubbles. Why might the same experiment produce two different answers? Does the difference between the 45^Oand 60^O results fall within the experimental error? Is the real answer somewhere in between, perhaps 50^O or 55^O ? Does the color of the tube, i.e. the viscosity of the liquid, make a difference? What are sources of error in the experiment, for example, what would be the effect of not holding the angle block tightly against the arm/base axis during each trial? How might the experiment be changed to answer these questions? How many significant figures should be recorded for the times?

With additional time, students can determine if the speed of the bubble is constant throughout the length of the tube. The procedure is similar to that of the first experiment. Students measure the time it takes to travel 10 centimeters, 20 centimeters, 30 centimeters, and 40 centimeters, conducting three trials for each distance. Distance traveled versus average time is plotted on a scatter chart. Does connecting the data points yield a straight line? Is the speed constant? Discussion can include speed as the slope of a line, and, particularly if you have a calculator which automatically calculates this value, standard deviation.

Leave a Comment » | Elementary Level, Experiments, High School Level, Middle School Level, Physics | Tagged: acceleration, collecting data, measurement, science fair project, speed, variables, velocity | Permalink
Posted by Tami O'Connor

Absorbent Spheres Help Students Soak Up Scientific Principles

March 14, 2012

by: John Fedors

GROWING SPHERES

Hydrophilic spheres from Educational Innovations offer a variety of interesting applications and opportunities for scientific inquiry. They come in a variety of sizes: small, regular, jumbo, & gigantic. For the following examples, I prefer the regular or #710 size. However, whichever size you choose, they will expand to about 300 times their original dehydrated size. As they absorb the water, they become almost invisible, due to having the same refractive index as water. When placed in de-mineralized or distilled water and kept away from sunlight, they will dehydrate to their original size and can be re-used. Dehydration time will depend on air humidity.

Once enlarged, these clear spheres can be used to demonstrate:

* The lens of an eye (such as those of a shark, calf or sheep) that has the ability to magnify the print on a page. A thin slice may be used to mimic a cornea transplant.

* The suspension of small items such as a coin.

* Roots of a germinating seed.

Enlarged growing spheres can also help to observe the relationship of Surface Area (A=4pr2) to Volume (V=4/3pr3) mass in grams. They can be used to graph relationships.

Using dark vegetable dyes you can also relate to why living cells need to divide. The ratio of surface area to cell volume does not permit timely diffusion of required metabolites in or out of the cell. This can be demonstrated by placing a dyed sphere in clear water for 10 minutes and measuring the clear area of the sphere in relation to the rest of darkened or dyed sphere.

My favorite though is the demonstration of cell organelles/microstructures in eukaryotic cells. In addition to the hydrophilic spheres, this demonstration requires serpent skin tubing. Serpent skin tubing is a crinkled cellulose dialysis tubing that stretches out, remains open and relatively sturdy. It eliminates the usual wetting difficulty in opening traditional dialysis tubing.

To demonstrate cell organelles/microstructures in eukaryotic cells you will need:

* Serpent Skin

* Small nut & bolt (to serve as weight)

* Twist Ties (used in grocery produce departments or with some trash bags)

* #710 Growing Spheres

* Tall glass

* Food Dye

* Distilled or de-mineralized water

Here’s what you do…

Take or cut a 6 to 8 inch length of Serpent Skin and flatten it. Fold it lengthwise 3 to 4 times, creating a long, narrow section. Fold the end up, then slide the folded end through the bolt. The bolt serves as a weight to keep the finished apparatus submerged in the dyed water. Use a twist tie between the bolt and then end of the tubing. I am a fan of the champagne twist – twist six times as you would see the wire is twisted on a champagne bottle top.

Place 25-35 Growing spheres through open end of the serpent skin and add 7-9 drops of dark vegetable dye to a tall glass. Add water to the glass up to an inch from the top or so. Place the weighted serpent skin with the growing spheres into the dyed water.

Results:

The dyed water will diffuse through serpent skin (cell membrane} and will cause the growing spheres to swell (this can take about 24 hours). The spheres will vary in size; larger spheres will collect towards the bottom of the glass while smaller spheres will collect towards the top. Adding more spheres initially will force them up and out. The varying sizes will help to visualize different organelles.

The dark stained organelles can be placed in clear colorless water for 5-10 minutes to demonstrate a colorless, clear outer surface area of diffusion. The spheres center will stay dark even after several water changes.

This also demonstrates the relationship of surface area to organelles volume and the need for the organelles to remain small for efficiency of passive diffusion.

Leave a Comment » | Biology, Chemistry, College Level, Elementary Level, Experiments, High School Level, Middle School Level | Tagged: dialysis tubing, hydrophilic, jelly spheres, organelles, osmosis, serpent skin tubing | Permalink
Posted by Tami O'Connor

The Owls Are Back!

February 6, 2012

by: Richard Yost

The owls are back . . . at least that’s the report we’re getting from a lot of our customers. If you have already been watching owls, you know how much fun is in store in the coming months as they lay their eggs, and then the young hatch and, then the parents bring in all those neat little tidbits of food . . . from moths and worms, to birds, mice, and rats. What a show!

If you don’t think you know enough to have owls in the backyard, think again. It may simply be because they don’t have a place for them to stay. You will be surprised at how quickly a pair will move in if you’ll take the time to mount an owl house.

Screech owls, Barn owls, Barred owls, Saw-whet owls and a variety of other owls are found in every state in the union, and many are surprisingly urban. Several years ago one of our customers sent in a picture of a barn owl house attached to the side of a building facing out onto an alley, with a dumpster right below it.

As an added bonus, some of the hawks, such as kestrels,will take up residence, and, of course, the squirrels are also sure to stop by.

For years I’ve watched “my” Screech owls via a Hawk Eye Nature Cam mounted in the inside upper corner of the nest box. The box is only 10-15 feet off our back patio. From that vantage point, however, all we see much of the time is the back of the parents’ head. The only time we get a full view of the chicks is when the parents are out hunting.

Owls are quite comfortable living close to people.

So, I’ve tried mounting the camera at various positions, with varied results, along the side and the front of the box. Ultimately, I found that high up, on the front edge of the box gives the best view, especially when it comes to feeding time. I also tried a camera at the bottom, front of the box. At this location I did get some spectacular, up close, in your face views of the baby owls eating, but most of the time, someone was sitting nearly on top of the camera, and so the view was only of out of focus feathers. But then again, there were so really spectacular scenes, as you’ll see in the video below.

Here’s an easy way of mounting a Hawk Eye Nature Cam in another position other than the inside corner of the box:

1) Buy a 45-degree, 2” PVC elbow at the hardware store. Get the kind that has a straight, non flared leg at one end, and a flared leg on the other.

2) Insert the camera and either screw or Velcro it into place. I screwed mine into a wooden plug that I slipped inside the flared end of the elbow, and then screwed that into place.

3) Use a keyhole drill bit to make a hole in the side of the box. Be sure to keep this plug, so it can be used to reseal the hole if need be.

4) Simply slip the PVC elbow into the hole. You might need to wrap a layer or two of tape around the outside to assure a tight fit. Also tack the camera cable somewhere on the side of the box to help keep the camera in position.

It's not pretty, but this owl house has seen its fair share of baby owls

Also remember that all of the action isn’t always inside the nest box. Try mounting a Hawk Eye Nature Cam outside the box, aimed up toward the entrance hole. Because of the camera’s wide angle lens, it doesn’t have to be very far away to capture the arrivals and departures of the parent owls.

Simply take a 1” x 2” x 24” board and screw it diagonally into the bottom of the nest box. Then screw the Hawk Eye into the end. Be sure to cover the camera to protect it from the rain.

To see the four different kinds of views you can expect from these camera positions take a look at our Setting Up an Owl Video Box, video. Also, take a look at our demo video Birdhouse Spy Cam Video to see the kinds of scenes you can watch and record.

The Birdhouse Spy Camera can be purchased at Educational Innovations online at www.teachersource.com. We encourage our customers to share what they are seeing in their owl boxes. Please post comments and video clips on our Facebook page at http://www.facebook.com/hawkeyecam, or send it to Richard@birdhousespycam.com