## 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.

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.

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.

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!

## Dinosaur Mania!

May 6, 2012

by: Michelle Bertke

Both the young and old have a special fascination with dinosaurs.  From the small Nemicolopterus to the larger Sauroposeidon, dinosaurs were magnificent and majestic creatures.  This is a topic students want to learn and adults want to teach.  Luckily, there are many at-home experiments and activities that parents can do to foster their children’s love for dinosaurs.

Impression Fossils

Impression fossils are one way that animals and plants, which are long since gone from this world, leave their mark.  One easy way to show how imprint fossils are formed is with play dough and plastic creatures.  Students can use the play dough (which is easily homemade) as a medium in which to press the plastic creatures.  This will leave an impression with a certain amount of detail.  Have the students compare the fossil imprint with their creature or mix up the imprints and play a matching game.  Use this activity to illustrate what can be determined from an imprint fossil (size or texture) and what cannot be determined (color).

Layers of the Earth

To take the discussion of fossils to a next level, an easy at-home activity is a display of the layers of the earth.  In order to create this you will need a plastic or glass container and different substrates to layer.  These can include sugar, coffee, rocks, dirt, or aquarium rocks.  Start the layering with finer material such as the sugar or coffee.  If you begin with the rocks, the finer dirt will fill in the cracks and the layers will become indistinguishable. As you layer the material put small objects in the layers such as fossils or plastic creatures.  This activity not only illustrates that the earth is made of layers but archeologists can determine where the fossils are located how old the fossils are.  In order help determine age you can add a diagram on one side of your container illustrating this point.

Fossil Dig

Parents can take dinosaur learning even further with at-home fossil digs and fossil sorting.  This is a great activity to help kids appreciate the intricacy and excitement of discovering fossils in their own home.  To make your own fossil dig you will need soil, plaster (that can be found in most craft stores), and fossilsThe consistency of the fossil dig will be based on the ratio of dirt to plaster mix.  The more dirt you have the easier it will be to dig the fossils out.  I recommend basing the mix on the amount of time you have allotted for the activity and the age of the group.  Once the ratio is decided on, mix plaster, dirt, and water together to create a mud with a consistency that allows it to flow without being too runny.  Pour the paste mix into individual disposable container.  Once the containers are filled, push fossils into the mix and set aside to dry.  Once dry, the fossils can be dug out with utensils and tools, from plastic knives to paint brushes.  In addition to digging for the fossils, kids can sort the fossils with supplied fossil sorting sheets in order to better appreciate the role of archeologists.

## The Pollution Spill and the River

May 4, 2012

by: Brian Herrin

### A Working Model of an Environmental Disaster

How to model a chemical spill in a flowing water system using connected siphons

One of the difficulties of modeling a flowing water system is the size of the system and the quickness of the flow.  This often makes demonstrations hard to visualize as things happen so quickly.  The model I designed uses large transparent plastic cups and clear tubing that connects them to easily demonstrate how a river can become contaminated by a toxic spill or dump and how the toxic material slowly works its way downstream creating devastation along the way.  In time, the river will eventually run clean, but the damage takes much longer to disappear, and some damage may be permanent.

Begin by setting up a mock river system using six to ten separate cups.  There is no limit to the number of cups you can use.  The siphon tubes used to connect the cups are made of 6.4mm (inside diameter) clear tubing cut into 40cm lengths.  You can use aquarium tubing and smaller plastic cups but a slower system will result.  You will need one less tube than the number of cups you use.  For a self emptying system, you can insert a smaller tube into the last cup that empties into a larger container.

Each cup in the river should be filled 1/3 with water with water-filled siphon tubes between each cup in the line, as in the diagram above.   To fill a siphon tube, lower one end into a filled pail of water and then slowly lower the other end of the tube into the water allowing the air to escape.  When the tube is completely filled cover the ends with your index fingers, lift the tube out of the pail and place the ends of the tube into two of the side by side partially filled cups above, releasing your fingers when the tubes are under the level of the water in the cups.  If you get a small bubble in the tube, lift one of the cups to allow the bubble to be forced out of the tube by the flow of water from a higher to a lower level.  Repeat until all the cups are connected and the tubes are completely filled with water.  Any large air bubbles may disrupt the flow so be sure to remove the excess air.

Add 2 tbsp (30ml) of an acid base indicator to each of the cups.  This can be made by cutting up a few red cabbage leaves into small pieces and placing them in one cup (250ml) of boiling water.  A much easier way is to use Red Cabbage Extract from Educational Innovations.  The infusion should turn a purplish color.  If it is not dark enough, remove the cabbage pieces and put in another chopped up leaf or two or add a little more extract.  Next, add a pinch (no more) of baking soda (sodium bicarbonate) to each cup.  When the baking soda is placed in the cups of red cabbage solution it should turn the solution in the cups a light blue.  You should now have all the cups filled to the same level with a light blue solution connected by clear, water-filled tubes.  It is essential that all the tubes be filled with water and all the cups are the same color before you introduce your “toxic spill”.

Although the water is not flowing at this time, this is now a model of the river before the “toxic spill”.  Inform your students that each cup represents only one section of the river.  Tell a hypothetical story about railway tank cars carrying a toxic liquid that traveled alongside the river.  Explain that there was a derailment on the way, and the tank cars tipped into the river spilling the liquid.  Mention that the toxic material spilled into the river will ‘kill’ living organisms in the river.  Use the model to explain that if the blue river water receives enough of the toxic material to kill the wildlife in the river, the toxins will turn the water pink.

Now use four or five fast-food vinegar packets to simulate the train cars.  Open them and empty the “toxins” (vinegar) into the first cup.

You should see the water in the first cup immediately change color to pink. Begin adding plain tap water to the first cup.  You will notice that if you pour slowly, the water will gradually siphon into the next cup.  As the water in the first cup (with a higher level of liquid) moves into the next cup, the “toxic waste” will begin to contaminate the second cup.  The result is that the water flowing through the tubes into each subsequent cup will change from blue to pink until eventually, all the cups are pink demonstrating contamination.

By placing a 50cm smaller, water-filled tube made from aquarium tubing into the last cup and draping it over the edge of the table or chalk ledge you can let it pour into a pail so your river will keep flowing as the cups gradually empty.

If you keep adding water to the first cup your model river will gradually run clear. You do not need to have a tube if you empty the last cup now and then without losing the siphon effect.  Emphasize that the model river has cleaned itself but the organisms that have died are gone and until the river repopulates from upstream or downstream where the toxic chemical has been diluted enough, the river will be ‘dead’ along that stretch.This is a very powerful model that is not soon forgotten, and if you accompany the demonstration with the information surrounding a real chemical spill or a toxic seepage into a river, it is a real eye opener on how much damage can result.  Something to remember is that we all live downstream from somewhere else.

## 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 apparatus

hook/loop strap (optional)

data tables

per class of 30 students: 3 each of 15O, 30O, 45O, 60O , 75and  90blocks.

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  45or 60produced the speediest bubbles.  Why might the same experiment produce two different answers? Does the difference between the 45and  60 results fall within the experimental error?  Is the real answer somewhere in between, perhaps  50O  or 55O ? 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.

## 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:

* Small nut & bolt (to serve as weight)

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

* 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.

## 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

Richard Yost is the founder of Birdhouse Spy Cam, which sells miniature video cameras for bird and other wildlife viewing.