Slippery Substances and Lubricants

Lesson Plan #: AELP- ENG0020

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An Educator's Reference Desk Lesson Plan
Submitted by: Rebecca Sexson, Anasazi Elementary School, Scottsdale, AZ
Endorsed by: These lesson plans are the result of the work of the teachers who have attended the Columbia Education Center's Summer Workshop. CEC is a consortium of teacher from 14 western states dedicated to improving the quality of education in the rural, western, United States, and particularly the quality of math and science Education. CEC uses Big Sky Telegraph as the hub of their telecommunications network that allows the participating teachers to stay in contact with their trainers and peers that they have met at the Workshops.
 

Date: May 1994

Grade Level(s): 3, 4

Subject(s):

  • Science/Engineering
OVERVIEW: Slippery Substances are called lubricants. They are very important in modern technology. Cars, trucks, airplanes, and machines all have parts that rub against one another. These parts would heat up, wear down, and stop working if we did not have lubricants. Lubricants reduce the amount of friction between 2 surfaces that move against each other.

OBJECTIVE(s):

Students will be able to:

1. Demonstrate which lubricant is best (slipperiest), of those used for the experiment.
2. Explain how a lubricant works. 3. Identify objects that need lubricants to work well.

RESOURCES/MATERIALS:

Teacher Materials = 4 envelopes unflavored gelatin, 8 inch square baking pan, mixing bowl, liquid dish detergent, vegetable oil, 2 bowls, clock or watch with a second hand, a knife, measuring cup Student Materials = pencil, science journals

ACTIVITIES AND PROCEDURES:

  1. Dissolve 4 envelopes of gelatin in a bowl of 2 cups of hot tap water.
  2. Coat the inside of a 9 x 12 inch pan with vegetable oil. Pour the gelatin mixture into the pan and refrigerate until firm (about 3 to 4 hours).
  3. Cut the gelatin into cubes about 1x1x1 inch, with a knife. You should have about 64 cubes.
  4. Place 15 cubes into a bowl. Place the second bowl about 6 inches away from the cube bowl.
  5. See how many cubes can be transferred to the other bowl in 15 seconds by using your thumb and index finger one at a time. (Don't squeeze!) CAUTION: Children should be cautioned not to eat the gelatin cubes after they have been handled or after they are covered with lubricant.
  6. Return all the cubes to the first bow. Pour 1/4 cup dish detergent over the cubes. Gently mix the detergent and the cubes so that the cubes are well-coated.
  7. Use the same method as before to transfer as many cubes as possible in 15 seconds.
  8. Throw away the cubes and detergent and wash and dry both bowls. Put about 15 new cubes into one bowl and; pour 1/4 cup water over the cubes, again making sure the cubes are thoroughly coated. See how many cubes you can transfer in 15 seconds.
  9. Throw away the cubes and water. Put about 15 new cubes into one bowl. Pour 1/4 cup of vegetable oil over the cubes. Make sure they are well coated. See how many cubes you can transfer in 15 seconds.
  10. Analyze your findings. With which liquid were you able to transfer the most cubes? With which liquid were you able to transfer the fewest cubes? Which was the best lubricant (the slipperiest)? Which was the worst?
    11.
TYING IT ALL TOGETHER: Students should now understand vocabulary words such as lubricant, friction, gravity, force, momentum, and machine. This is an ideal activity to follow a study of simple machines. Mr. Gumpy's Motorcar, written by John Burningham, is a good introduction and motivator. Students should be able to list objects that have working parts that would need lubricants to protect their parts, such as cars, trucks, bicycles, etc.