Estellvenia Sanders  [Chicago Vocational HS]         (Chemistry):  Combining Substances
Estellvenia divided the class into two groups, and gave each group a set of 5 empty test tubes.  She had supplies of 4 different liquid detergents, as well as corn starch and baking soda.  A sample of four liquid detergents was poured into each of 4 test tubes by each group --- a different detergent in each of the group's test tubes.  The 4 detergents apparently had different densities.  She asked us in what ways are the different detergents similar?  Do they .merely have different percentages of water?  Are there other differences?

We put baking soda into 2 of the test tubes that contained detergents, and recorded what happened.  When baking soda was added to the green detergent, it turned blue, and a chunk of the baking soda sank to the bottom of the test tube.  In the yellow detergent a chunk of baking soda floated slowly to the bottom; no color change.  We concluded that the blue detergent contained a pH indicator.  The detergents seemed to be of different density, with the yellow one containing less water than the blue one, because of the different sinking rates for the baking soda.  When we added corn starch to each detergent in turn, it stayed as a clump at the top in each case.  Then we added "neutralizer" (an unspecified clear liquid) to each test tube -- the neutralizer stayed as a layer on top of the detergent in the absence of mixing, forming what a molecular biologist would call a step (density) gradient.

This lesson had been developed by one of Estellvenia's students --- the best in the class!  We studied the lesson and made the following comments on it for Estellvenia and her class:

• The viscosity of the detergent, as well as its density, determines the rate at which solids fall through it.
• Probably there is no decomposition here.  We do see some signs of separating and settling, but there do not seem to be any chemical changes.
• This exercise is an excellent discovery lesson.
• Maybe we should do the experiment twice --- once all the way through with each of the 4 detergents
• Perhaps we should be more quantitative, weighing out amounts, measuring the volumes, etc.

Marva Anyanwu [Green Elementary School]         Apple Model of the Earth
Marva started by asking why we thought an apple might be a good model of the earth.  Our answers included the facts that it has a core, it has a skin (crust), it contains layers, and it contains a visible axis.  Also, an apple -- like the earth itself -- will get rotten if it is not given proper care.  We then followed these procedures:

• CUT THE APPLE INTO QUARTERS
  Three quarters represent that part of the Earth covered by oceans.  Set them aside.
• CUT THE REMAINING QUARTER IN HALF
  One piece represents areas where few people live:  polar areas, deserts, and swamps.  Set them aside.
• CUT THE REMAINING PIECE INTO QUARTERS
  Three of these quarters represent land that cannot be used for growing crops.  Set them aside.  The last piece of the apple represents that portion of hte earth on which crops can grow.
• PEEL THE SKIN OFF THAT PIECE
  The skin represents the layer of topsoil that is used to grow food for nearly 6 billion people.
• Why do you think soil conservation is so important?

Food for thought and graphic excellence! Thanks, Marva!

Jane Shields [Calumet HS, biology]         Low Stress Learning
Jane called attention to the fact that Barnes & Noble University [http://www.barnesandnobleuniversity.com], Virtual University [http://www.vu.org], and The Fathom  Knowledge Network [http://www.fathom.com]  provide lectures and courses in a variety of topics for self-paced learning.  In addition, she called attention to the Star-Online Educational Network [http://www.star-online.org], which has modules that provide CPDUs [continuing Professional Development Units] through the ISBE.

Thanks, Jane!

Bradley Wright [Eisenhower HS, Blue Island]         Chemist's Recipe for Chocolate Chip Cookies
Brad brought in the recipe, which is given on the website The Chemist's Recipe for Chocolate Chip Cookies: http://f2.org/humour/cooking/chem-cookie.html.

Delicious as well as educational!  Thanks, Brad!

Notes taken by Benjamin Stark.