Ann Parham and Winifred Malvin [Carver Elementary
Making Erasers (Handout)
Anna and Winifred helped us study polymers by making erasers. We added vinegar to an an aqueous latex solution, with food coloring added for visual enhancement. We obtained a rubbery solid, avoiding contact with the skin and using eye protection. We could form the rubbery mass into various different shapes, which would harden upon drying for several hours.
An additional experiment used an abrasive (sand mixed with baking soda) to make an ink eraser (remember them?). The exercise involved chemical reactions, with acids and bases, polymerization reactions, and modifying the physical properties of polymer obtained. These lessons come from the book Chain Gang -- The Chemistry of Polymers, which can be obtained from Terrific Science Books, Kits, and More™. For details see the website http://www.amazon.com/Chain-Gang-Chemistry-Polymers-Science/dp/1883822130. The table of contents for that book can be seen at http://www.amazon.com/Chain-Gang-Chemistry-Polymers-Science/dp/1883822130#reader_1883822130.
Great job, Ann and Winifred!
Carol Giles [Collins HS] Styrofoam
Carol shared an exercise she uses in her special education class. She passed out Styrofoam® packing nuggets, and asked us how many nuggets would dissolve in liquid Methyl Ethyl Ketone (MEK -- CH3-CO-C2H5), a chemical compound closely related to Acetone (Methyl Methyl Ketone -- CH3-CO-CH3). We watched with awe as handfuls of nuggets were dropped into a beaker with 200 ml of MEK, as they melted down and disappeared. The original colorless, odorless solution became very dark green, as the pale green nuggets dissolved. [Note that ordinary melting involves a change from solid to liquid phase of a material without the addition of other reactants, whereas this is quite different.] The original nuggets consisted mostly of air, and they actually contain very little polystyrene foam -- Styrofoam®. Other objects made from Styrofoam® (coffee cups, plates, ... ) can also be used. Results may vary, when different amounts of MEK are used. Acetone, a less expensive ketone, may also be used to dissolve Styrofoam®. Carol uses this exercise to demonstrate the scientific method.
Pat Riley emphasized the importance of doing this experiment in a well-ventilated room, away from heat sources to avoid respiratory distress and inflammation. [For a description of the hazards of MEK, see the website http://www.tapplastics.com/msds/pdf/MSDS_MEKS.pdf. Acetone presents similar hazards!] Pat suggested an alternative version using water-soluble starch-based packing pellets.
Interesting stuff, Carol!
Chris Etapa [Gunsaulus Academy]
Constructing Models of
Cells and Organelles
Chris showed us models of cells with labeled parts, which were made by her 7-8 grade students. The students could prepare a model, or do a research project on cells. We were very impressed by the artistry and creativity of her students. Here is a brief summary of the project assignment:
Brenda Daniel [Fuller Elementary School] and Erma Lee [Williams
School] Edible Plant Parts
Erma and Brenda followed up their presentation at the previous meeting by handing out this List of edible plants (roots, seeds, fruits, leaves, and pods):
|carrots||peas||artichokes||avocados||Brussel sprouts||green beans|
|Jerusalem artichokes||pumpkin seeds||bananas||bell peppers||beet greens||okra|
|leeks||sunflower seeds||berries||cranberries||cabbages||sugar snap-snow peas|
A deliciously interesting lesson, Brenda and Erma!
Notes taken by Ken Schug.