Objectives

To demonstrate the power of observation and to learn about superabsorbent polymers

Materials

• Water gel
• Scoop
• Three Styrofoam® cups
• Water
• Shower cap
• Towel

Procedure

Put one scoop of water gel in one of the cups prior to doing the investigation (scoop comes in the packet of water gel).  Do not let your audience know you have water gel in the cup! Place the three cups on a flat surface. Fill one of the other cups half full of water. (It does not have to be exact.) Tell the children that good scientists have keen observation skills and to watch carefully. Move the cups around on the table, mixing them up. Ask someone to tell you which cup has the water in it. Hopefully, they will get the right answer! Again, tell them to observe carefully. Repeat, pouring the water into the second empty cup. Finally, pour the water into the cup with the water gel. Mix the cups around on the table for the third time. Ask another member of the audience which cup has the water in it? Pick a good sport in the group (one unafraid to get wet) to come up front for the demonstration. You can really play this up to get the group excited; use your acting skills! Turn all three cups upside down over the volunteer’s head, one at a time…the two empty cups first and finally the one with the water gel. They are fully prepared to get wet. What happened to the water? Where did it go?

Conclusion

The children will learn about superabsorbent polymers and how important it is to be a good observer at the same time! One scoop of water gel in a cup of water will instantly change from a liquid to a solid. (This is why nothing came out of the cup when it was turned upside down.) The chemical name for water gel is sodium polyacrylate, or Hydrogel, and it absorbs from 800 to 1000 times its weight in water. It's the secret ingredient that is used to absorb "liquid" in baby diapers. Yuk! (You can buy a jar of water gel at a science supply store or online.)