Indirect Observation

Belvon Walker                  Frazier School
                               4027 West Grenshaw Street
                               Chicago, Illinois 60624
                               312-534-6880

Objectives:
    
    The student will
      1.  observe the external obscertainer (these are sealed containers that 
          come with the Lab Aids #100 kit).
      2.  make hypothesis on internal structure of several obscertainers.
      3.  retest each hypothesis.
      4.  check observation again, correct internal structure on each.
      5.  develop an appreciation of indirect observation and make the
          connection between this activity and the historical determination
          of the molecular structure of matter.
  
Material needed: 

   For a class of 25:
      1.  25 sealed obscertainers
      2.  students worksheets
      3.  answer sheets
      4.  crayons

Strategy:

      1.  Instruct the students not to open the containers.
      2.  Tell the students that each container has one (1) steel ball inside 
          each container.  They may have none to several internal wall 
          structure(s). 
      3.  Demonstrate the possible internal wall structure on the board.
      4.  Give each student four (4) obscertainers.  Instruct them to move the 
          steel ball around carefully by shaking and tilting the obsertainer.  
      5.  Ask students to make a guess about the internal structure of each 
          obcertainer and to draw this structure on their worksheet. 
      6.  Note that the first guess is called a hypothesis.  
      7.  Tell the students to re-examine each obcertainer and make a second 
          guess about its structure.  Draw each second guess next to the 
          hypothesis drawing.  Call this second guess the "retest". 
      8.  Discuss how much information could be obtained without actually 
          looking inside. 
      9.  Make a connection between this activity and scientist trying to 
          determine the structure of molecules and atoms too small to be seen. 
          
 References:  

      Lab-Aids kits can be purchased from the following scientific supply 
      houses:  Central Scientific Company; Fisher Scientific; Wards Biology  
      Supply.  All three companies will furnish catalogues upon request.