Playful Polymers

Nancy Mosher                   Infant Jesus of Prague School
                               1101 Douglas Ave.
                               Flossmoor IL 60422
                                708-799-5200

Objectives:

Eighth grade students will be able to complete a performance assessment 
demonstrating their knowledge of polymers by:
     1.  Determining the properties/characteristics of polymers.
     2.  Discussing the relationships between types and uses of polymers.
     3.  Describing the molecular structure of polymers.

Materials needed;

Each group of two to four students will need the following material:

Ziplock sandwich bag           sharpened round pencil          balloon
wooden skewer                  quart size Ziplock bag          white glue
2 stirring rods                liquid starch                   paper towels
2 small plastic cups           5 or 6 plastic or rubber objects per grade
5 or 6 non-polymer objects per grade
20 ml of 4% Polyvinyl Alcohol Solution (PVA)
3 ml of 4% Sodium Borate Solution (Borax)

Strategies:

Activity I:
1.  Blow up a rubber balloon about half-way.  Do not make the balloon taut.
2.  Place a little cooking oil on the tip of a sharpened skewer and push it 
    completely through the balloon from where the balloon is tied to the nipple, 
    without popping the balloon. 
3.  Discuss with the class what they think is happening and why.
4.  Fill a Ziplock plastic bag 3/4 with water.  Push a sharpened pencil 
    completely through the bag. 
5.  Once again ask, "Why do you think the bag does not leak?"  "Is there a 
    similarity between this and what happened to the balloon?" 
6.  Give each group a bag of water and have them push pencils through the bags. 
7.  Have the class compare what happens to the bag with what happened to the 
    balloon.  Ask them to discuss the similar properties of the balloon and the 
    bag.  See if they can think of any other substances that have these 
    properties.  Have them hypothesize what they think is happening in both 
    instances. 

Activity II:
1.  Give each group a plastic bag filled with 6 items that are polymers and 6 
    items that are not. 
2.  Each group will sort the objects into two categories:  Polymers or plastics 
    and non-polymers or non-plastics. 
3.  Have various groups compare their classifications and come up with some 
    agreement about the classification of each item. 
4.  Together discuss how each item was sorted and what characteristics or 
    properties they used to sort the items. 
5.  Together list the characteristics that are common to the plastic/polymer 
    group. 

Activity III:
1.  Have each group brainstorm polymers and come up with as many items as 
    possible that are made up of polymers. 
2.  Have the groups discuss the relationship between the characteristic 
    properties of the items and their uses. 

Activity IV:
1.  Discuss with the class what the term polymer means.
2.  Give background about molecular structure of polymers.
3.  Discuss synthetic vs. non-synthetic polymers.
4.  Have each group link hands to represent a polymer chain.
5.  Have one group become crosslinks and bond the polymer chain together.

Activity V:
1.  Make a crosslinked polymer - silly putty.
2.  Mix 2 tablespoons of white glue with 3 tablespoons of liquid starch.
3.  Stir and work glue into mixture.
4.  Form the polymer into a ball and rinse under water.
5.  Squeeze the polymer while rinsing.
6.  Examine its properties.
7.  Discuss why it is a polymer and what makes it a crosslinking polymer.

Activity VI:  PERFORMANCE ASSESSMENT
     Have each student complete the following performance assessment to prove 
that they understand polymers and their molecular structure.

Assessment:

     In your secret laboratory, hidden away in the Andes Mountains, you finally 
make the most important discovery of your scientific career.  You make a 
remarkable crosslinking polymer.  You carefully perform the following steps:
    
     1.  Pour 10 ml of 4% Polyvinyl Alcohol Solution (PVA) into a small cup.
     2.  Measure 1.5 ml of 4% Sodium Borate Solution (Borax).
     3.  Add the Sodium Borate to the PVA and stir.
     4.  Remove the gel and knead it.

While kneading the gel, you slowly, and scientifically examine the substance and 
study its properties.

     You decide to sell the formula to the International Polymer Company that 
happens to have a branch office across the valley from your secret lab.
In order to sell this new product you must do the following:

     1.  Prove that your substance is a crosslinking polymer.
     2.  Prove that your substance's properties are "new and improved."  What 
         makes your polymer better than any other.  (Be sure to do this as 
         scientifically as possible and be sure you have enough data to support 
         your claims.) 
     3.  Show the molecular structure of your substance.  Prove that your 
         substance is better than any similar non-polymer by being as graphic as 
         possible. 
     4.  Finally, based on its properties, what creative new uses does your 
         substance have?  What can the International Polymer Company do with 
         your new polymer based on its remarkable properties. 

REMEMBER! ! !  To really sell your product, you must be clear, exact,
 scientific and organized.  Good Luck!

Rubric:

     Assessment will be based on a rubric with points ranging from a score of 0, 
not attempted, to a score of 6, exemplary response.  The exemplary response 
should contain the following information:

     Gives a clear, coherent and elegant explanation of:
     - numerical data using scientific measurement
     - a chart, graph or table
     - a list of at least 5 characteristics
     - a comparison of this gel with other polymers
     - an explanation and diagram showing molecular structure and crosslinking
     - proper use of at least 5 new vocabulary words
     - creative uses for each property of this new gel (slime)

References:

Physical Science. 1991. D.C. Heath Company, p.499-505.

"Plastics", Wonder Science. Volume 5, Number 5, December 1991, American Chemical 
Society/American Institute of Physics.