Materials You’ll Need Elmer's glue Borax powder Measuring spoons Water Food coloring (four colors) Small plastic cups, straws, or spoons for stirring Paper towels Exploration Mix 1 tablespoon of Borax in 1 cup of water and stir until dissolved. Label 4 small cups #1, #2, #3, and #4.  Add 2 teaspoons of the Borax solution to cup #1, 4 teaspoons to cup #2, 6 teaspoons to cup #3, and 8 teaspoons to cup #4.  Add a small drop of food coloring to each cup--a different color for each. To make "goop," add 1 tablespoon of glue to a cup and stir until a glob forms. Compare the properties of the four polymers in terms of the following properties. How well do they stretch?  Rank them in terms of their "stretchability" (#1 being the least and #4 being the most stretchable). How well do they bounce?  Rank them in terms of their "bounceability." How well can they be molded?  Rank them in terms of their "moldability." How well do they retain their shape? Form a ball and let it sit on the table for a few minutes.  Rank them, with #1 being the flattest and #4 the most rounded. Create a series of graphs, listing the 4 polymers across the bottom of the graph (the x-axis) and their ranking for stretchability, bounceability, moldability, or shape retention on the y-axis.  What can you conclude about how cross-linking affects these properties?