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Kathleen Cummings Dominguez Sabin Magnet
2216 W. Hirsch
Chicago, IL 60622
Students will demonstrate a greater understanding of "friction" by
cooperatively experiencing and describing a range of phenomena involving
friction. Students will understand the term "static friction" and the ratio
of friction and weight as it relates to moving an object at rest.
For each student: wooden sticks, (i.e, popsicle, candied apple and chop sticks)
one empty thread spool
metal, plastic, cork and rubber washers
rubberbands, assorted sizes
For each group: set of slotted weights
small pan (plastic, from microwave dinners) with a hole for
tying the string
For teacher's demonstrations:
Two identical, cylindrical, glass bottles (with tops), filled with various
quantities of water
One wooden slope, at least as wide as the bottles, with sandpaper glued to
the reverse side* and two 2" X 4" X 8" blocks
The teacher wears a pair of jeans with worn knees and a shirt or sweater
with worn elbows
Various surfaces for lunar vehicle runway: smooth, *sandpaper, large frozen
tray of ice, carpeting, etc.
One "slimey" ball
One crystal wine glass half full of water
Detergent for washing hands and vinegar
One spool of thin string
One pre-made "air car" made from a thread spool, cardboard square and a
Foam rubber mats of different textures, 24" X 24"
Column of coins
1. Teacher throws a "slimey" ball on the chalkboard and asks students how the
ball moves. She rubs an edge of a wine glass to get the glass to sing. She
asks the class how it happens. If they don't know, they are told friction did
it. Students are asked to rub their hands, then really hard, and tell what
happens. The teacher rotates the sound tubes so the students can hear and asks
the class what makes the sound.
2. Teacher asks students, grouped into cooperative teams, to list examples of
friction and then to write a good definition. Answers are written on the board.
Class synthesizes answers into one good definition. Students are led to
understand that friction can be associated with solids, liquids and gasses and
that there are subtle examples as well as flagrant examples. Teacher asks
individual students to move a column of coins with one finger on the top of the
column. (Teacher demonstrates how to do it: by pressing hard on the top coin on
the edge closest to her).
3. Students are shown how to make a "lunar vehicle" with the thread spool,
various rubberbands, washers and sticks. Students are to predict and/or test-
out the best type of components to use which will most effectively use friction
to make the vehicle run. Students test their lunar vehicle on various surfaces,
i.e., wood, sandpaper, rug, ice and table top. Each group selects its best
lunar vehicle to compete with other teams in a race on the indoor/outdoor
4. Teacher asks groups to predict what will happen with the two bottles which
she is about to let roll down an incline. Students will understand that water
creates friction on the glass and slows down and stops that bottle's movement
sooner than the empty bottle stops.
5. Teacher asks teams to predict what will happen to the contraption called an
"Air Car" when she lets it go. Students will learn that air can reduce friction
and overcome gravity.
6. Each group is given a little parachutist, asked to throw him/her into the
air, observe and write an explanation as it relates to friction. Each group
reads their answer to the class. Students will learn how air can be used to
oppose the force of gravity.
7. Groups experiment with various weights and friction using the pan, string,
weights, spring scales and various surface textures. The groups are asked to
collect data as weight is added to the pan. Students will understand the ratio
between weight and the force required to move the weight to overcome static
friction, i.e., to move a mass from rest.
Coefficient of Friction: mu = FFR/N