Densities

Ellice M. Norman               Teachers Academy for Math and Science
                               10 West 35th Street
                               Chicago IL 60616
                               (312)808-0100

Objectives:

     This activity will help the middle school student understand the concept of
density.  Students will develop and utilize skills in observing, predicting and 
testing.  Students will understand the concept of density as it relates to 
liquids, solids and gases.

Materials Needed:

Grapes                                              Paperclips
Molasses                                            Corks
Oil                                                 Pieces of a candle
Water                                               Woodchips
Red and blue food colorings                         Yellow clay
Pickling salt                                       Density Results Sheets
Plastic cups (6oz.)                                 Medicine droppers

Strategies:

1.  Advance preparation:  Make two salt water solutions.  The first consisting 
    of 2000ml water, 600ml pickling salt and 20-30 drops red food coloring.  The 
    second solution will contain 2000ml water, 300ml pickling salt and 20-30 
    drops blue food coloring.                   
2.  Make "impure" clay by mixing woodchips with clay, forming this into the 
    shape of a crown. 
3.  Read the story of the king and Archimedes and tell the students that we will 
    experiment with our crown to determine if it is pure or impure.
4.  Weigh pure clay of equal mass as that of the crown.
5.  Determine the volume of the crown and the pure clay by immersing them
    one at a time into a full container of water.  Measure and record the amount
    of displaced water for each object.
6.  Distribute to each of four groups:  Molasses, cooking oil, red solution,
    and blue solution (4oz. of each in plastic cups)
    4 medicine droppers
    10 plastic cups
    1 paperclip
    1 cork
    1 candle piece
    1 grape
    Hypothesis/Results sheets 
7.  Explain to the students that they are now going to hypothesize and 
    experiment with the densities of the liquids before them.  The students will 
    weigh each of the four liquids and make hypotheses on the ranking of the 
    liquids from least dense to most dense.  Their hypothetical ranking will be 
    recorded on the Hypothesis/Results sheets.  After making their hypotheses, 
    students will begin layering the four colored liquids into a plastic cup one 
    color at a time.  As soon as the colors mix, try a new combination.  
    Students will continue experimenting with different combinations until they 
    have layered the liquids in order from most dense to least dense.  Record 
    the results.  The students will pour all remaining liquid, in the proper 
    order, into an empty plastic cup.  They will then hypothesize, ranking the 
    solids from least dense to most dense (they will weigh the solids in order 
    to make their hypotheses).  After recording their hypotheses on the 
    Hypothesis/Results sheet, students will drop each of the solids, one at a 
    time, into the cup containing the layered liquids.  Students will then 
    record the actual order of the solids by density and compare the differences 
    between their hypotheses and their actual results.  They will then write a 
    paragraph on what they observed. 

Performance Assessment:

The student must complete the Hypothesis/Results sheet and observation paragraph
with 100% accuracy.

                     Density Results Activity Sheet

Please hypothesize ranking the liquids from the heaviest to the lightest in 
density then write the actual ranking.

         Hypothesis                                   Actual
1.  ____________________                      ____________________
2.  ____________________                      ____________________
3.  ____________________                      ____________________
4.  ____________________                      ____________________
5.  ____________________                      ____________________


Please hypothesize ranking the solids from the heaviest to the lightest in 
density then write the actual ranking.

         Hypothesis                                   Actual
 

1.  ____________________                       ___________________
2.  ____________________                       ___________________
3.  ____________________                       ___________________
4.  ____________________                       ___________________
5.  ____________________                       ___________________


Please write a paragraph explaining your observations about your hypotheses
compared to your actual test results.