The Marvels of the Molecule

Douglas Xavier Key                    Douglass Math and Science Academy
                                      543 North Waller
                                      Chicago IL 60644
                                      (312)534-6176

Objectives:

Grades 5-8.

Describe the concept of the molecule.

Create a model of a water molecule.

Explain molecular theory.

Use phenomenological approach.

Materials Needed:

Water molecule model: Peach, cherries.

No heat demonstration: Handkerchief, small glass, rubber band.

Fire syringe demonstration: Fire syringe, flame paper.

Station #1: Cola bottle, balloon.

Station #2: Baby food jar, Straw, red/blue food coloring, clay.

Station #3: Notebook paper, paper hole punch, small glass, toothpick.

Station #4: Paper cup, toothpick, water.

Strategy:

     I will use hands-on experiments so the class will be able to identify 
molecules moving or attracting each other.  Students will create water and 
methane molecule models, demonstrating how they are shaped.
     After discussing how molecules are shaped the class will work at four 
different stations.
     At Station 1 the kids will try to inflate a balloon inside a bottle.  The 
balloon will not inflate because of air already present in the bottle.  If you 
would like to expand this experiment, direct the children to try to inflate a 
balloon inside a plastic two liter bottle.  After they are done trying this, 
punch a small hole at the bottom of the small cola bottle and the two liter 
bottle.  Then try blowing into the balloons.  The balloons should inflate 
because the air inside the bottles is escaping through the hole in the bottom 
allowing the balloons to expand and inflate. 
     At Station 2 the groups will do an experiment demonstrating the forces of 
gravity.  In this experiment, the children will lower a straw into clay placed 
at the bottom of the jar that has colored water in it.  They will quickly turn 
the jar upside down, pouring the water out.  There should be water left inside 
the straw but not the jar.  The air inside the straw pushes up on the water when 
the jar is inverted and water molecules are pulling from side to side.  These 
forces are greater than the downward force of gravity; thus the water remains in 
the straw. 
     At Station 3 the group will observe the movement of paper circles that seem 
to have a mind of their own.  In this experiment the children will fill a cup 
3/4 full of water.  When the water is calm, they will place a paper circle on 
the surface in the center.  The paper circle should float to the side of the 
cup.  After removing the paper, fill the cup to overflowing with water.  When 
the water is calm,  place the paper circle in the center.  The paper circle 
should remain in the center.  Surface water molecules pull on each other, but 
they are more attracted to the molecules in the glass.  This attraction causes 
the water to be pulled toward the glass.  The glass that is overfilled with 
water does not have the exposed glass sides for the water to be attracted to. 
     At Station 4 the group will observe separate streams of water forming one 
stream when pinched together.  In this experiment the children will punch four 
holes in a cup.  The holes should be as close together as possible in a straight 
line 1/4 inch from the bottom of the cup.  Fill the cup with water.   Take your
thumb and finger and pinch the four streams of water together.  There should now 
be one stream of water forming. 
     It is very important to explain to the children that they will have to note 
their results from their four experiments in their science notebooks. 

Performance Assessment:

     Students should be able to define molecule and draw a model of a water 
molecule.  Students' knowledge of molecules should be greatly enhanced after 
performing the four experiments.  Oral discussion will follow the experiments
to further develop the concept of molecules.

References:

     I would like to thank the many people that helped me with my mini-teaching 
lesson.  I would especially like to thank my mentor, Barbara Pawela for her help 
and support, Ed Guzdziol, Jake Carter, Ed Metzl, and Pat Riley for their many 
exciting experiments.