GadgetOff 2009

October 20, 2009

KenByrneby:  Ken Byrne

Ron Perkins and I had the privilege of being invited to share some of our favorite EI products at GadgetOff 2009. GadgetOff is an exhibition that includes people on the cutting edge, not just of technology, but also science, the arts, education, and the future in general.

There were so many amazing presentations that I don’t know PIC_0275which one was my favorite. Much of what we saw was just plain fun. There were two variations on an amusement park carousel, only they were powered by pulse jets. We also got to see pumpkins hurled by a trebuchet that must have been eighteen times the size of our Advanced Trebuchet Kit. But perhaps the strangest sight there was PIC_0298eight-foot diameter mechanical spider brought by a team from Vancouver. This gas-powered, hydraulically actuated monster was driven around the field like a bulldozer. It made me want to build a robot in my basement…or buy a tarantula.

There were also more serious and life-changing presentations. Segway inventor, Dean Kamen, shared with us the progress on his latest project, a prosthetic arm unlike any other. It has fully articulated human-like fingers, not a simple clasp or hook. It allows the user to pick up an egg or a grape without crushing it, and  enable the user to tell the difference between the two. All the servos, processors, sensors and everything else associated with the prosthetic arm weigh in at under three pounds!

We met dreamers, visionaries, and inventors. One group specialized in projecting large-scale artwork onto the sides of buildings using lasers. Through this, they met an artist that has been struck with amyotrophic lateral sclerosis (ALS), also known as “Lou Gehrig’s Disease.” This artist has been paralyzed below the chin for years. They developed and inexpensive eye-movement tracking system that has now given him a mean of communication, as well as the ability to make art again.

So, what did we share with these visionaries. It was a difficult choice. The other invitees showed great interest in our Mirage Illusion, especially when using it with a laser. They all mir100knew that the image of the pig floating above the Mirage was an illusion, so were amazed that you could still hit it with the laser beam.

Ron also demonstrated his BB Board, a devise of his own design. With it you can easily explain how molecules reorganize when hs12heat-treated, show movement of geological formations, and visualizing the motion of solid liquids and gas particles.

Everyone also loved the sneak preview of our new device for transmitting sound using a common laser pointer. This device will be available soon. Look for the announcement in our newsletter.

As always, one of the favorites was the FunFlyStick. This is our mini Van de Graaff van200generator with its floating toys that seem to defy gravity.

We truly appreciate the opportunity to attend GadgetOff and are grateful to Michael and Dan for extending yet another invitation to us this year!

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Posted by Tami O'Connor

Goldenrod Paper

October 1, 2009

ronby: Ron Perkins

Color changing goldenrod paper has been exciting students of all ages for decades to the wonders chemistry! Imagine the enthusiasm of the first student or teacher who spilled a few drops of ammonia on a piece of yellow paper and observed it turn bright red! One can only image them exclaiming: “Super, Wow, Neat!!!”

Place the paper in a solution of household baking soda and the paper turns red; immerse it in vinegar and the red turns back to yellow! This goldenrod paper is colored with a dye that is an acid/base indicator: red in base and yellow in acid. The paper is similar to litmus paper that is blue in base and red in acid.

Even though color changing, goldenrod paper is no longer being manufactured, Educational Innovations, Inc. still has a supply and the paper is being sold in 100 sheet packages, (#SM-925). This special paper was being manufactured until Junesm925 of 2008. At that time the process was changed to use a different dye that is more cost effective and better for the environment. Currently, paper of the same color, Galaxy Gold, is being offered by retail office supply stores, however, this paper uses a different dye and is not color changing.

Simple Activities With Goldenrod Paper

1. Write a “secret” message on the paper with paraffin or candle wax. The invisible message can be seen by spraying or wiping the paper with a weak basic solution e.g. ammonia (NH3 (aq)) or baking soda (NaHCO3). If you use ammonia solution, the message will disappear when the ammonia evaporates. If you use a baking soda solution, the message will remain.

2. Write a message on the paper using a cotton swab dipped into household ammonia. As the ammonia evaporates, the red message disappears.

3. Repeat Activity #2 using a cotton swab dipped into a solution of baking or washing soda. The message can be erased using vinegar (HAc) as “Yellowout .”

4. Use goldenrod paper to classify household products as acidic or basic. Solutions that turn yellow paper red are bases; solutions that turn red paper yellow are acids; and solutions that do not turn the color of either paper are considered “neutral.”

5. Tape a piece of yellow goldenrod paper to the board. Dip your hand into a shallow container of baking or washing soda and water. Then, when you press your hand against the paper, you will leave a “bloody” hand-print. Especially useful at Halloween. Compliments of Bob Becker 1985, Greenwich High School

6. Sponge the surface of a piece of goldenrod paper with a baking soda or washing soda solution and allow the wet, bright red paper to dry. Then, tape the paper to the board and press a hand that has been dipped into vinegar against the paper. The yellow hand-print will be the reverse or the “negative” of the result in activity #5. Complements of Carl Ahlers 2008, Australia

More Advanced Activities with Goldenrod Paper

7. Sponge a solution of baking soda or washing soda on a piece of goldenrod paper. Observe that the red color becomes gradually darker. Explain? Carl Ahlers has written: “Drying shifts the equilibrium in reaction 1 to the right as the H2CO3 is reduced due to the evolving of CO2 gas (reaction 2) (Le Chatelier). Subsequently more of the red Gol forms on drying. HGol (yellow) + HCO31- <—> Gol1- (red) + H2CO3 (aq) Reaction 1 H2CO3 (aq) <—> CO2 + H2O Reaction 2

8. Determine the equilibrium constant, the Ka, for this acid/base indicator. One way is to prepare a set of different pH solutions using a method of serial serial dilution on a spot plate or in small test tubes. Then, test to see at what pH the color change seems to occur for this indicator paper.

9. Make color-changing paper similar to goldenrod paper using household tumeric powder. Although tumeric is insoluble in water, in a workshop at Sacred Heart University, ca 1987, we discovered it was soluble in either ammonia or ethyl alcohol. White paper dipped in a solution of ammonia with dissolved tumeric will be dyed red which turns to yellow as the paper dries; dipped in a solution of tumeric and alcohol, the paper will remain yellow as it dries. When dry, test and observe how similar and how different the paper is from the color-changing goldenrod. Note: although this paper seems to react similar to color-changing goldenrod, the color fades much faster.

10. Prepare acid/base color changing paper using natural indicators: rose petals, purple cabbage, etc. Then determine the pKa of the paper.

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Posted by Tami O'Connor

Heat Sensitive Paper

September 11, 2009

ronby: Ron Perkins

A short time ago I received the following inquiry regarding our Heat Sensitive Paper. One of the joys of being the president of Educational Innovations is having the opportunity to answer questions like this.

Q: What chemical coats your Heat-Sensitive Periodic Tables that makes it change color? My chemistry class wants to know the chemistry of what is happening. Can you pleasehea300 help us.

A: Some of the characteristics of our heat sensitive periodic tables are easy to understand and some more challenging. The inks used provide color at lower temperatures and are colorless at higher temperatures. The change over temperature is called the “critical temperature.” Adding heat to the paper causes the paper to loose its color, an “endothermic” reaction. The reverse, going from colorless to colored, is an “exothermic” reaction and returns the heat.

To manufacture this paper, long rolls of white paper are unwound, coated on one side, dried, cut, and finally stacked into reams. This is done at a company that produces labels for cans. The paper is then printed with black ink to produce our periodic tables.

Educational Innovations, Inc. was one of the first companies to sellhea200
thermochromic paper and drinking cups, over 15 years ago. We followed up on an article about this new discovery in the NY Times. At that time the “Touch-It” paper used two colors of heat sensitive inks: blue and red – both turning colorless when heated. From those two heat
sensitive inks, five colors of paper could be manufactured: red paper
which turned colorless; blue paper which turned colorless: orange
paper which turned yellow; green paper which turned yellow; and purple
paper which turned colorless. For the orange and green paper, the
thermochromic inks were printed on yellow paper.

The complete chemistry of thermochromic, heat sensitive ink, involves micro-encapsulation techniques. Incidentally, you can increase the sensitivity of your periodic table by removing any absorbed moisture with a hair dryer or putting the paper through a copy machine.

I have found that kids of every age find this paper fascinating. Teachers use this paper to print newsletters home to parents, for special certificates or awards, and for printing diagrams or other papers the students should keep. They can even be laminated to use as bookmarks, hall passes, or as class syllabus.

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Posted by Tami O'Connor

Back To School Fun

September 8, 2009

tamiby: Tami O’Connor

Though I am no longer in a traditional classroom, the end of each August still fills me with that feeling of eager anticipation and yes, even a bit of anxiety…. Then I remember, I’m not going to be facing a room filled with bright new faces nor will I need to develop the plethora of creative lesson ideas necessary to engage and stimulate young minds. But still, I enjoy sharing some of the lessons that my students and I enjoyed.

One activity I used to teach the scientific method required the use of an old favorite; Sodium Polyacrylate. This is the chemical powder found in disposable baby diapers. I would start my lesson with a 3 Cup Monty game in which I used 3 opaque cups that were identical in every way except that two of the cups were empty and in the third I placed about 3 tablespoons of the water lock powder.

My shtick started with me talking about the importance of observation skills. I would explain the necessity of having a keen eye. Shortly after my speech I would pour about 1/2 of a cup of water into one of the empty cups. While encouraging my students to carefully watch the cup with the water in it, I would move the cups around fairly slowly, knowing they would be able to follow the water filled cup easily, until the three cups ended in a line across my desk.

When the motion stopped, I would ask the class to identify the “water” cup. When they did, I would pour the water from the “water” cup to the other empty cup and repeat, only this time I would move the cups a bit more quickly. Since I am admittedly not very fast, most of my students were able to identify the “water” cup on the next try.

I continued two or three more times complimenting my students’ observation skills as they identified the correct “water” cup each try. On the last try, I would pour the water from the “water” cup into the cup with the powder hidden in the bottom. As you can imagine, the water was quickly absorbed by the sodium polyacrylate and solidified leaving no liquid behind in the cup.gb6

On the final trial I moved the cups as quickly as I could trying to distract the students as much as possible as I shifted, bobbed, and weaved… I even stopped from time to time to point out the elusive leprechaun poking his head in the window, and while a few kids turned to look, I unfairly continued to move cups. Finally, when I sure I had fooled at least a few kids, I stopped.

With my three cups neatly lined across my desk, I would call on one student to identify the “water” cup. After pointing out the suspect cup, I flipped the chosen cup over to show there was no water in it. Try number two provided the students a 50-50 chance of identifying the “water” cup. Of course, one more wrong pick… Since I have already mentioned that I am fairly slow, chances were good that one of the chosen students had identified the correct “water” cup earlier, but because of the sodium polyacrylate, when I turned the cup upside down, the solid water remained stuck inside the cup.

There is always at least one student in the class who insists that the cup with the water in it has already been selected. I tend to call that student up to the front of the class to prove that their observation skills are the most astute by challenging them to stand under the last cup while I pour out whatever is inside it over their head. I build up the anticipation by having the guinea pig don a rain jacket…

While the class would cheer (and jeer) I would make quite a production of the cup over the brave (or foolish) student’s head being filled with water. As you already know, when I turned the final cup over, amid the oooooh’s and aaaaah’s, no water came out, and my student stayed dry. Imagine, three cups empty cups now, where at one point, at least one had water. There was no doubt, I had everyone’s attention

No matter what the grade level, this lesson is sure to generate interest. Now, everyone knows that you can have a terrific introduction, but the lesson has to have teeth in order for our students to learn. There are a number of activities you can launch into immediately following this introduction.

  • What is the ratio of water to powder that sodium polyacrylate will hold?
  • What are the chemical differences between the water loc and snow polymer?
  • Which baby diaper holds the most water?
  • Why does adding salt to the solid water reverse the effect of the absorption.

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Posted by Tami O'Connor

The Amazing Ostrich Egg

August 27, 2009

KenByrneby: Ken Byrne

The ostrich is a member of the Ratite family, which also includes emu, rhea, cassowary, and kiwi. Ratites are distinguished as flightless and keel-less (having no breast bone) birds. Ostrich skeletons and fossils date back over 120 million years.

The ostrich, native to Africa, is the largest of living birds. Some males reach a height of 8 ft (244 cm) and weigh from 200 to 300 lb (90 – 135 kg), while females will range between 5.5 and 6.5 (170 cm – 200 cm) feet tall at maturity.

In the wild, a mature female will lay between 12 and 15 eggs after mating (at the rate of one every other day for several weeks). Ostrich farmers quickly remove the eggs from the nest to extend the laying season. In some cases, a domesticated hen can lay up to 80 eggs, although 40 to 50 is more typical. Ostrich eggs are the largest of all bird eggs and weigh about 2.75 pounds (1.2 kg). The contents of one ostrich egg can be equivalent to as much as two dozen chicken eggs. Both male and female ostriches share sitting responsibilities, usually the male at night and the female during the day. Fertile eggs begin to hatch on the 42nd day.

Ostrich eggs are as beautiful as they are fascinating, and they areost100 surprisingly durable. Artists paint them, cut them and even decorate them with intricate carving. The Bush Men of the Kalahari Desert use them as sturdy canteens that can hold about 1.25 liters of water.

Educational Innovations has ostrich eggs that have been emptied through a hole in one end and thoroughly cleaned. The somewhat mottled, glossy surface is natural.

Ostrich Egg Activities:

How big a breakfast?
Fill your ostrich egg with water and measure the contents. Now measure the fluid that comes from a regular chicken egg. Comparing the two, can your students determine how many omelets could be made from your ostrich egg? Can they estimate the mass of the egg before it was emptied?

Discussion Topics:
Is it accurate to say that an ostrich egg is the largest single cell in the world today?
Why is the shell of an ostrich egg so thick?
Eggs shells are made of calcium. Where do ostriches, and other birds, get the calcium to produce hard shells?

Super! Neat! Wow! Ostrich Facts!

• Ostriches cannot fly.
• Ostriches produce extremely strong leather.
• Ostriches are not an endangered species – there are at least 2 million worldwide.
• Ostriches are one of the fastest animals in the world. They can sustain a speed of 40 miles per hour (64 kph) for 30 minutes!
• Ostriches do not bury their head in the sand. They lie down and extend their neck along the ground when threatened.
• The ostrich egg is the largest bird egg in the world today, but not the largest ever. That distinction goes to the elephant bird. Its eggs were up to 90 cm in circumference, and could hold 9 liters! They’re extinct now but may have walked the earth as recently as the mid 17th century.

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Posted by Tami O'Connor

Real Amber

August 24, 2009

tamiby: Tami O’Connor

What is Amber?
Millions of years ago large forests in some parts of the world began to seep globs of sticky, aromatic resin down the sides of the trees. Unlike sap, resin is produced to protect the tree from disease and injury and is extruded through the barkamb100 of the tree during rapid periods of growth.

As it continued to ooze, this resin would trap such things as insects, seeds, leaves and other light debris. As geologic time progressed, these forests were buried under sediment and the resin hardened and formed the soft, warm golden gem we know today as amber. Most of the amber in the world ranges from 30 to 90 million years old and is found in sedimentary clay, shale and sandstones associated with layers of lignite.

Amber is found in the far-corners of the world and is mined from the ground. It can be found from the shores of the Baltic Sea (Poland, Russia, Germany, Denmark, Lithuania), to mountain ranges in the Dominican Republic and Columbia. There is also Romanian, Burmese and Canadian Amber. Amber can be found in the United States and is most abundant in Alaska and New Jersey. This amber dates back to the Cretaceous Period, the age of the Dinosaurs! The size of amber found varies tremendously. The biggest piece of Dominican amber ever found was 18 pounds!

Amber can be hand or machine polished. Professionals use machinery such as sanding wheels to polish amber. They first start with coarser grit levels of sandpaper and as material is removed and they get closer to the surface, they switch to less coarse grit levels to add final touches. Final polishing can be done with a cotton buffing wheel and dental polishing compound. For amber jewelry, holes are drilled with a very fine drill bit. Experts must be aware that amber is sensitive to extreme heat.

Amber actually has the ability to develop a static charge when rubbed with a cloth. In fact, the source of the word electricity is from the Greek name for amber elektron.

The Copal vs. Amber Debate
Copal is a younger form of amber. Much of it from Columbia is said to be up to 10 million years old. Over the past several years, it has become available in great supply. Dealers who sell other types of older and more rare amber, such as Baltic or Dominican, due to their commercial interest, have been trying to convince others to not classify copal as a type of amber. Many scientists disagree, stating that anything made from resin IS technically amber, despite its age.

amb200In the movie Jurassic Park, the storyline was that dinosaur DNA had been retrieved from insect remains found in amber, allowing them to regenerate dinosaur life for the park. Though there are actual insects found embedded inside some amber, this is just a story. Scientists have never been able, in real life, to do this.

Beware! There are actually counterfeit producers of amber who make fake amber using living insects and synthetic resins. Experts have tests to confirm what is real or fake. At Educational Innovations, our amber is real. We only purchase our amber from reputable miners who guarantee authenticity.

Educational Innovations has a terrific hands-on lesson to use with your students as a culminating activity for your geology unit or unit on dinosaurs. This class kit comes complete with everything your students will need to clean and polish actual pieces of amber. Your students will all leave your classroom with a small sample piece as each kit includes 8 one-inch pieces of amber for polishing and 17 smaller amber samples The kit also includes 25 plastic bags to secure samples, 8 polishing brushes, amber polish (aka: gel toothpaste), sandpaper and a complete teacher’s guide. This activity is perfect for the elementary and middle school classroom.

Kit Contents

• 8 large pieces of rough amber to use for class activity
• 17 small pieces of rough amber
• 25 plastic bags for students to secure their amber samples
• 8 polishing brushes
• Tube of amber polish
• 2 Sheets of sandpaper (9×11)

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Posted by Tami O'Connor

Sink Your Teeth Into Some Shark Facts

August 19, 2009

LaurieNby: Laurie Neilsen

In honor of The Discovery Channel’s Shark Week, here are some common questions asked about shark teeth, and some meaty facts to sink your teeth into.

Q. Why are some shark teeth black and others are tan?

A. The color of a fossil shark tooth is dependent upon the sediment in which it settled. As minerals slowly replace the calcium in the tooth, it changes to the color of the minerals. Color does not necessarily indicate age in a shark tooth fossil. It usually indicates the region from which the tooth was collected. Our rm-11fossilized shark teeth are collected from Morocco.

Q. Then how old are these fossil shark teeth?

A..It’s hard to say. A shark tooth takes approximately 10,000 years to become a true fossil. These teeth could be as much as a few million years old!

Q. Why are there only fossils of shark teeth and vertebrae, but not their other bones?

A. A shark’s skeleton is made of cartilage. This makes the shark flexible and fast, and provides buoyancy, precluding the need for a swim bladder like other fish have. Only the teeth and vertebrae of a shark are calcified enough to turn into fossils. Without calcium, the cartilage eventually disappears, and does not become a fossil.

Q. Do sharks have molars?

ps-300A. No, sharks do not have molars, incisors, or bicuspids like humans have. Shark’s teeth are all the same shape, but vary in size throughout the mouth. Each species of shark has a different tooth shape, making it easier to identify and sort the fossil shark teeth by species.

Q. Are sharks hunted for these teeth?

A. No, the shark teeth we sell were collected from beaches, not from live sharks. A shark will lose thousands of teeth throughout its lifetime. While the teeth are calcified for strength, they are not as firmly attached in the mouth as our teeth are. Sharks have rows of teeth to provide added grip when they bite their prey, and so they always have replacement teeth ready to take the place of the ones that fall out.

Most sharks live and hunt in coastal waters, though some have been tracked going far out to sea and traveling many miles throughout the course of a year. When the sharks lose teeth while hunting near the shore, these teeth settle in the sediment, fossilize, and sometimes eventually wash up on the beach. Many teeth are also collected by divers close to the shore.

Shark populations are declining because not only are they over hunted, but there have been many man-made changes in their environment. Many shark species are becoming endangered. Sharks are hunted out of fear and misunderstanding, but they are also hunted for trophies, and for their fins. The practice of shark finning – catching sharks just to collect their fins for shark fin soup, and throwing the injured sharks back into the water to drown – is one of the leading causes of the decline in population. For more information on sharks and shark week, visit the discovery channel website at: http://dsc.discovery.com/convergence/sharkweek/sharkweek.html.

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Posted by Tami O'Connor

Compressed Air as a Force

July 31, 2009

Normby: Norman Barstow

When the National Research Council produced the National Science Standards in 1995, they did so without including sets of lesson plans nor did they design them as part of a standard curriculum package. They were written to be used as goals for our students’ achievement in science.

In my classroom I always used the National Standards when designing my lessons, and they were always clearly represented in the objectives I set for my students. I have found that the topics of Force and Motion, as well as Air, (as part of a weather unit), can be easily taught using balloons to demonstrate the concepts of each. I have designed two different lesson activities that can be used to meet the following standards.

National Science Standards
Content Standards: K-4
Physical Science; Content Standards

  • An object’s motion can be described by tracing and measuring its position over time.
  • The position and motion of objects can be changed by pulling or pushing. The size of the change is related to the strength of the push or pull.

National Science Standards
Content Standards: 5-8

  • The motion of an object can be described by its position, direction of motion and speed.
  • An object that is not being subjected to a force will continue to move at a constant speed in a straight line.
  • If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on the their direction and magnitude. Unbalanced forces will cause changes in the speed or direction of an object’s motion.
  • Energy is transferred in many ways.

Balloon Rockets
In a recent workshop I attended, which presented a module on Air and Weather, ‘Balloon Rockets’ was an activity used to show that compressed air can exert pressure to propel a balloon rocket.

The activity used a straw threaded through fishing line, which was stretched across the room. A ziplock bag was then attached to the straw, and the inflated oblong balloons were launched by placing them into the open bag. The force produced by the balloon propelled the straw along the fishing line.

I noticed that the balloons tended to make the bag move from side to side, thus decreasing the distance traveled. We tried the activity again using balloons directly attached to the straw with masking tape. The oblong balloon traveled much farther than the ziplock bag attempt. Next, I introduced the Educational Innovations Rocket Balloons. BalloonOnALineWhat a difference, both in distance traveled and speed. The Rocket Balloons release the compressed air steadily from the opening of the balloon to the weighted tip thereby pushing the straw farther along the fishing line.

Balloon powered car

Another recent discovery I made in my basement was a compressed air (balloon powered) car that I saved from an NSTA workshop I had once attended. The ‘car’ was built with a piece of cardboard as the frame and an axle system made using a wooden skewer inside a drinking straw. The ‘wheels’ were bottle caps and the ‘engine’ was a straw with a balloon attached.

BalloonPoweredCar

While the oblong and/or round balloons worked fine, I wanted to try the EI Rocket Balloon. I had to modify the ‘car’ to account for the increased length and mass of theBalloonPoweredCar2 rocket balloon. The new chassis was now 4 X 14 inches, and I moved the wheels accordingly for this ‘super sized’ car. Again, the difference increased significantly in both distance and speed.

In addition to meeting the above National Standards, these are perfect experiments for elementary and middle school students on manipulating variables and testing hypotheses using the scientific method.

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Posted by Tami O'Connor

Slime, Gak, and other Gross Science

July 24, 2009

tamiby: Tami O’Connor

Let’s face it, kids of every age love gooey substances! The year is never complete until you have made at least one version of slime. Depending upon your grade level, the topic you’re teaching, your classroom budget, and the time you have available, there are a number of options open to you.

One of my favorite “recipes” is the ever popular Elmer’s Glue Gak. Aside from the fact that it’s easy to make, it’s rare that you wouldn’t have most of the essential ingredients at your fingertips.

Borax-and-ElmersYou will need equal parts of Elmer’s glue-all and water. I tend to use two cups side by side and pour about 1/4 cup of glue in one and an equal amount of water in the other. Students can easily judge if the two liquids are equal without messing around with measuring cups. Pour the glo100water into the glue and stir well. At this point, you can add food coloring, or better yet, phosphorescent powder so your gak will glow in the dark. If you’re using food coloring, only 4 or 5 drops are necessary.

In a separate cup you will need to mix hot water and Borax (sodium tetraborate) until you have a saturated solution. 20 Mule Team Borax can usually be found in your grocery store in the laundry aisle. I explain to my students that the water is saturated when the powder no longer dissolves in it. Evidence that you have a saturated solution is when the powder remains on the bottom of the beaker or glass even after the liquid is stirred well.

While mixing the glue mixture, slowly add the Borax solution. Students will immediately find that the glue mixture begins to clump and turn from a liquid to more of a putty-like solid. This is because the sodium tetraborate is a cross linking agent that hydrogen-bonds with the long polymer molecules found in the Elmer’s glue.

Another favorite gooey activity is slime making…. For this, I always use polyvinyl alcohol. I love using the hot water soluble sm8Polyvinyl Alcohol Bags commonly used in hospital laundry rooms. Typically, these bags are used to place soiled linens within them reducing the chance that a hospital worker will come into contact with contaminants. When the bag, filled with sheets etc. is thrown in the washing machine, the hot water dissolves the bag exposing the linens to the water and detergent. When the water leaves the washing machine, so does the dissolved PVA.

sl1

To make the slime, dissolve the PVA bags in hot water (the appropriate amount is in the directions), and then slowly stir in the same Borax solution used to make Gak. The basic difference between slime and Gak is textural and color. Gak is opaque while slime is more transparent, and slime tends to be a little thinner and less putty-like. As with Gak, slime can be colored by using a couple of drops of food coloring before adding the Borax solution.

sl300For those teachers who have less time to spare, Educational Innovations carries a Classroom Slime Kit that has everything you need premixed. All you have to do is combine the PVA solution and Borax solution and voila… instant slime!

Finally, the gross fluid that behaves like a liquid and a solid; Oobleck! When allowed to sit in its container, Ooblek behaves like a liquid. As soon as pressure is applied, this non-newtonian fluid behaves like a solid. It can be rolled into a ball, but then as soon as you stop rolling, it “melts” in your hands! Kids love experimenting with this material!

Oobleck is easily made by using 2 parts cornstarch to one part water. If you are planning to color your Oobleck, it’s easiest to color the water you add to the cornstarch. Finally, if you are working with younger children, the perfect literature connection is Dr. Suess’s Bartholomew and the Oobleck.

Clean-up for any of the gooey mixtures is fairly simple. A warm soapy sponge should clean most flat surfaces. It’s a good idea to keep any of the polymers away from clothing or carpeting, especially if you use food coloring. With the exception of the Borax solution, I would avoid putting anything else down the drain, but putting them in the garbage can should be fine… Be sure there is a plastic liner in the can or you will not be the custodian’s favorite teacher!

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Posted by Tami O'Connor

High School Density

July 22, 2009

ronby: Ron Perkins

Whether teaching general science, chemistry or physics, one of the first experiments I assigned was to determine the density of a metal using a set of different sized cylinders of aluminum in a tray.

Each Student:

  • Determined both the mass and volume of a single assigned sample.
  • Recorded their data point on a large classroom Mass vs. Volume Graph.
  • Participated in a class discussion on: determining volume by different methods; drawing a straight line through the data points (including the origin); and calculating the slope of the line (rise over run)

Density Graph-sample

Ron’s suggestions:den122
1. The set of aluminum cylinders (DEN-102) or PVC (DEN-120) are ideal beginning sets. The brass set (DEN-110) is interesting as one can determine the percentage of brass and zinc from the density using a CRC Handbook. The Polypropylene set (DEN-132) is interesting because the specimens float.

2. The Density Mystery Set (DEN-202) uses the element of surprise to teach students to trust their data. The set is made of two different black polymers, each with its own density. When the data is plotted, two different straight lines are produced, each with its own slope or density. Typically students will assume that the material is all the same and start questioning their own measurements. About half of the samples sink in salt water and half float

den2203. Our most popular set provides samples of 12 different substances (DEN-212). Also popular are the cubes of 6 metals (DEN-220). Once students have mastered mass and volume measurements, they find it interesting to be able to identify a substance by determining its density.

Advantages of using our Density Kits:

  • Students learn that the density depends upon the ratio of mass to volume and not upon size of the sample.
  • Students observe that some methods for determining volume are more accurate than others.
  • Students discover that the slope of the “best” straight line usually gives a more accurate density value than calculating from a single piece of data.
  • The teacher can immediately tell from the data points if a student needs help in measuring.
  • The teacher can quickly see if all of the samples have been returned at the end of class.

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Posted by Tami O'Connor

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