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Hello!  When I make polymers like Glurch or Slime with a class, I 
make a People Polymer to help illustrate how simple molecules (the 
monomers) link chemically to form a long molecule (polymer).  Steps 
1-4  below represent chemical bonds forming. Step 6 is a physical 
entangling of a long molecule.

You'll need a magic wand (represents the catalyst, a high-energy 
molecule that starts the reaction).

1.  Ask students to form pairs facing each other and holding both 
hands.  Sometimes this is the deal-breaker, but persevere.  If you 
have an odd number of students, let that unpaired child have the 
magic wand.  These pairs of kids represent a C=C double bond in a 
monomer like ethylene . . . C2H4 . . . it becomes POLYethylene soon.

2.  Use the wand to tap on one of the linked hands of a pair of kids. 
Just these two hands let loose, and one kid gets the magic wand. 
Whover had the wand to start grabs hold of the loose hand of that 
pair.  Remember, the wand represents lots of energy--it's a "free 
radical," or an unpaired electron.  You might have heard of free 
radicals and anti-oxidants in green tea.

Maybe a video would be clearer!

3.  Wand holder now taps on one of the linked hands of another pair 
of kids.  Again, just the tapped hands let loose, and a new kid gets 
the magic wand.  Previous  wand-holder now grabs hold of the loose 
hand of that pair.

4.  Keep it going!  It's a chain reaction . . . the "hot end" of the 
growing polymer chain "attacks" a new monomer molecule.  Peacefully, 
of course.

5.  When you get all the pairs of kids attached in a long chain, DO 
NOT link up the ends.  It just wouldn't happen in a real 
polymerization reaction with gabillions of molecules.  Often the 
growing end grabs an electron from something else, and the reaction 
is quenched.

That may be way more than you wanted to know, but it's really fun to 
do this, and I think kids do understand about small, identical 
molecules linking up in a longer chain (like beads on a chain).

6.  If you are on one end of the chain, you can weave around a bit 
and tangle up the chain.  Polymers are lots more viscous than 
monomers--glop, glurch or slime compared with the original 
ingredients.

7.  You can represent cross-linking with a few extra students who 
bridge across two parts of a chain of kids.  Borax-activated polymers 
are cross-linked with -B-O-B-O-  links.

8.  Oh, yeah.  You'd best un-polymerize everyone with the magic wand 
before they all have to ooze out the door.

I have a more elaborate molecular dance to show the reaction in a 
fuel cell:  breaking apart H2 and O2 molecules, "borrowing" the 
electrons (to light a lightbulb or whatever), and reassembling the 
bits into water molecules.

Still dancing, Jane

>Does anyone have a kinesthetic activity demonstrating the difference 
>between physical and chemical change, or physical and chemical 
>properties?
>Thanks!
>Alice Enevoldsen
>Planetarium and Stage Science Teacher and Enrichment Coordinator
>206-443-2883
>[log in to unmask]              Life's Boring Without Discovery!

-- 
Jane Snell Copes	  Science Outside the Box 
www.scienceoutsidethebox.com      651-357-3316 (cell)

Science Outside the Box is a tiny business that celebrates the 
scientist in every one of us.  I am a writer and teacher, and I have 
fun with science every single day.  I'm especially fond of designing 
classes and science magic shows for kids and parents. 


Science questions?  Ask Professor Sepoc:  [log in to unmask]

"To be an inventor, you need a good imagination and a big pile of 
junk."  Edison

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