## What is That Stuff?

November 3, 2010

by: Elaine Kotler

I created a lab using the Instant Snow Polymer (Sodium Polyacrylate) from Educational Innovations that I use in my 8th grade Physical Science Class as well as Summer School Programs that I teach for grades 4-9.  This lesson incorporates concepts of Conservation of Mass, Properties of Matter, Metric Measurement and Conversion, and Observation Skills.  The lab, as I give it to the students, is listed below.

Each student receives an empty baggie to be used for comparison, a baggie containing 12 grams of Instant Snow Polymer, use of a balance and a graduated cylinder.

I have already explained the Law of Conservation of Mass, and Density (they need to remember that the density of water is 1 g/ml, or look it up) prior to introducing this lab activity.  However, they do not know the terms exothermic, endothermic, hydrophobic or hydrophilic.  My students are allowed to look them up, but unless they make careful observations as they are conducting the experiment, they won’t be able to answer the questions later.

The final question “What is That Stuff?” garners some interesting answers. Some recognize a use for it as snow for ski slopes; others have suggested material for ice packs.  One suggestion was to use the powder to help clean up and absorb spills.

It is wonderful to see the faces of the students as they are in awe of what is occurring in the baggie.  I allow the students to color the water, if they so desire.  One year I did the lab on Saint Patrick’s Day.  Guess what color most students chose?

Elaine Kotler
Saint Paul School, Kensington, CT
Summer Options for Kids, West Hartford, CT
Kids on Campus, Middlesex Community College, Middletown, CT

What is That Stuff?

1.           Record mass of the empty baggie as given by Miss K (A)

2.          Without opening the baggie, use a scale to measure the mass of the bag with the contents in grams (B). Record data.

3.          Calculate the mass of original contents by subtracting the mass of the empty baggie from the mass of the baggie with the original contents.  Record data (C).

4.          Feel the contents of the baggie through the baggie and think about how it feels temperature–wise.

5.          Using a graduated cylinder, measure 160 ml of water. Record volume of water (D).

6.          Calculate the mass of the water. DO NOT MEASURE!!  Record data (E)

7.          Open baggie and add water to the powder.

8.          Immediately zip the bag closed.

9.          Shake the bag to mix the powder and water and watch what happens.  DO NOT OPEN THE BAGGIE.

10.       Without opening the baggie, take the mass of the baggie and its contents (F).  Record data.

11.        Calculate the mass of new contents by subtracting the mass of the baggie from the mass of the baggie and the new contents.  Record data (G).

12.       Feel the contents of the baggie through the baggie and think about how it feels temperature–wise.  Make careful observations.

13.       Add your measured mass for the original contents (C) and the calculated mass of the water (E).  Record data (H).

14.       You may now open the bag and play with the material.  It is non-toxic, however DO NOT PUT IN MOUTH.

15.        Clean up.

### Student Sheet

You must look up any terms you are unfamiliar with that are used in this handout.

Measurements and Calculations 10 points

A = mass of baggie (g) ____

B = mass of baggie and original contents (g) ____

C= mass of original contents (g) B – A ____

D = volume of water (ml) ____

E = mass of water (g) ____

F = mass of baggie and new contents (g) ____

G = mass of new contents (g) F – A ____

H = C + E (g) ____

What is That Stuff?

Questions

1.       Explain why you needed to measure the mass of the baggie during the experiment. (15)

2.      Explain how you arrived at your answer for E, since the mass of the water was not measured. (15)

3.      Is your answer to G the same as your answer to H (± 3 g for margin of error)?  Explain why or why not. (15)

4.      Is this reaction exothermic or endothermic?  Explain. (15)

5.      Is the powder hydrophilic or hydrophobic?  Explain. (15)

6.      And, finally, what is that stuff?  Describe it, give it a name and describe one use for that stuff. (15)

NAME _________________  Score ________ out of 100

## Bring Some Magic Into Your Classroom!

July 10, 2010

by: Ted Beyer

One of my favorite authors, Arthur C. Clark, once said, “Any sufficiently advanced technology is indistinguishable from magic.” This has been quoted, misquoted and reused for years.  Of course, it’s perfectly true, and magicians have been using science as part of their acts for centuries. Things that we take for granted today were once bleeding edge technology. I remember in high school reading that sometime ‘soon’ (this was more than 30 years ago) there would be TVs that would be so thin that they would hang on the wall like pictures – impossible! A generation before, the concept of television itself was astonishing, and a generation before that, moving pictures of any kind were magical.

As I started to think about this, I suddenly realized that there are many products that we sell here at Educational Innovations that are used – currently – by magicians as ‘tricks’ in their act. Let’s take a look….

Perhaps one of the most used and simplest items would be our Sodium Polyacrylate, which magicians know as ‘slush powder’ among other names. This hydrophilic long chain polymer relies on hydrogen bonding to bind with almost any water based liquid and create a gel-like mass, the volume of which is about the same as the liquid that you introduce. In simple terms, when almost any liquid comes in contact with this stuff, it almost instantly becomes a near solid. This is a quick and easy way for magicians to ‘vanish’ liquids in any number of tricks.

Magicians pay dearly to acquire this material, and yet it is readily available and used in many industrial applications. Perhaps the most widespread use is in disposable diapers.

A close cousin of ‘regular’ Sodium Polyacrylate is what we know as ‘snow polymer’ or Instant Snow.  Actually this is chemically identical to ‘regular’ Sodium Polyacrylate, and shares its hydrophilic properties, but since it has a huge number of cross links compared to the original form, it expands massively, and quite quickly, producing a mass of fluffy white ‘flakes’ that resemble snow in look and feel. This material also finds its way into a variety of illusions.

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I recently discovered that there is a product sold to magicians that is nearly identical to the Amazing Ice Melting Blocks . In the trick, the magician tells the audience that both blocks are identical (of course they aren’t), and that he will heat one block by bombarding it with his ‘psychic waves’ and cause the ice to melt. Magicians LOVE the fact that is uses real ice – in fact they can get it from audience members thus proving that it is real. The ice is placed on the blocks, and he concentrates oh-so-hard, and low and behold, the designated block melts the ice, and the ‘control’ block’s ice stays nicely whole…Presto!

Well — Thermodynamics! Of course one block is an insulator, and the other a conductor (plastic and aluminum in our version) that look practically identical. Heat transfer in the aluminum block ‘magically’ melts the ice, and the insulator preserves it.

In the classroom, this can be taken a step further: Allow the students to handle the blocks, and predict which one will melt the ice more quickly. Of course the aluminum block feels colder than the plastic block (it’s drawing the heat away from their hand more quickly), and so more often than not they will predict that the ‘cold’ block will preserve the ice. The look of amazement on their faces as the ice vanishes into a puddle in seconds is priceless (be sure to watch the video for the product).

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Here’s something that I think is amazingly cool – a wire that, no matter how misshapen, when heated will instantly spring back to straight. It’s Nitinol Wire, a sophisticated alloy of Nickel and Titanium that falls into a special class of materials called shape memory alloys. These can be set into new shapes using a jig to hold the wire in a specific shape, and then heat-treating it. Magicians use pre-set shapes (often in the shapes of the suits on a deck of cards) which can be shown straight, and only went placed into warm water or exposed to the heat of a lighter, do they “magically” spring back into their pre-set heart, club, etc. incarnation.

You can make your own shapes, and of course you can do the reverse – bend the wire into the shape of a rival school’s mascot, or their letter, and obliterate it with a quick dip into a cup of warm tap water, leaving the wire straight once more.

**********

As anyone who knows me will tell you, one of my two favorite products at Educational Innovations is the large Eddy Current tubes (the other is our Chinese Spouting Bowl).  The magicians have grabbed on to this physics concept as well, with products such as “Newton’s Nightmare’ and others.

“Newton’s Nightmare” consists of an aluminum tube with a series of holes down one side, a magnet, and a non-magnetic mass identical in appearance to the magnet. Using slight of hand, the magician can control which mass the audience member drops down the tube, and by doing so he can ensure that his will always take several seconds, and the audience member’s mass will drop just as you would expect it to – instantly. How does that work? Amazing!

Well, amazing physics anyhow.

A complete understanding of how eddy current tubes work is fairly complex, but in the simplest terms: Lenz’s law states that a magnet passing through a coil will produce an electric current. An eddy current tube can be made from any non-ferrous, electrically conductive material that acts as the ‘coil’.  As a magnet passes through the tube it creates the aforementioned electric current, and that, in turn, creates an electromagnetic field. The interaction of that electromagnetic field and the field of the permanent magnet cause the magnet to drop through the tube at a greatly reduced speed as compared to the effect of gravity.

Four factors determine just HOW slow it’s going to go: The conductivity of the tube (more conductive is better!) the power of the magnet (again, more is better), the thickness of the walls of the tube (once again, more is better), and finally how closely the magnet fits into the tube (tighter is better).

In the Large Copper tube (ED-100), the walls are quite thick, which allows us to use a smaller magnet. The advantage to this is that when you look down the tube, you can see ‘daylight’ all the way around the magnet as it falls slowly through the tube. Use a tighter fitting, more powerful magnet like our M-165, and the drop time more than doubles. Educational Innovations also has Eddy Current tubes in aluminum, and small, thinner walled copper tubes, one of which has a slit in it so you can see the magnet fall. There is even a monster one meter copper tube that comes with magnets yielding a drop time of over 25 seconds!

Hey, I understand how the thing works, but it STILL seems like magic to me!

## Back To School Fun

September 8, 2009

by: 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.

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.