TEACHER’S G UIDE
TEACHER’S GUI DE
TEACHER’S G UIDE
• Lead students through a discussion of how their lives would be different if there was no fri c t i o n . Build on the idea of the “love - h a t e
relationship” with friction by having a debate or by creating a twocolumn bulletin board supporting each side of the issue.
• H ave groups of students replicate the investigations from the show
to prove or disprove that fluid and rolling friction have less fo rc e
than sliding friction.
• H ave students identify the specific points in va rious sports activities
w h e re friction helps get things done or makes wo rk more difficult.
Internet Resources
Periodically, Internet Resources are updated on our Web site at
www.libraryvideo.com
• freeweb.pdq.net/headstrong/Hover.htm
The “Bizarre Stuff You Can Make in Your Kitchen”Web site lists two
diffe rent plans for building hove rcrafts, ve h i cles capable of almost
frictionless flight.
• www.iit.edu/~smile/physinde.html
This site lists over 200 lessons on basic physics concepts ge a re d
t owa rds middle and high school including some interesting ones
on friction.
• www.sci.mus.mn.us/sln/tf/f/friction/friction.html
The “Thinking Fo u n t a i n ” Web site from the Science Museum of
Minnesota describes a friction investigation with ball bearings.
Friction
Grades 5–8
TEACHER’S GUIDE
Conrad M. Follmer
25 years as a K–5 Science & Math Coordinator for a Pennsylvania public
school system, currently an independent consultant to elementary schools.
Paula J. Bense, M.Ed.
Curriculum Specialist, Schlessinger Media
Suggested Print Resources
• Arnold, Nick. Fatal Forces. Scholastic, New York, NY; 1999.
• Doherty, Paul. The Spinning Blackboard and Other Dynamic
Experiments on Force and Motion. Wiley Publishing, New York,
NY; 1996.
• Friedhoffer, Bob. Physics Lab in the Home. Watts Publishing,
Danbury, CT; 1997.
TITLES
• ATOMS & MOLECULES
• CHANGES IN PROPERTIES
OF MATTER
• CHARACTERISTICS OF WAVES
• ELECTRICITY
• ELEMENTS, COMPOUNDS
& MIXTURES
• FLIGHT
• FORCES
Teacher’s Guides Included
and Available Online at:
6/04
5
• FRICTION
• GRAVITY
• LIGHT
• MAGNETISM
• MOTION & BALANCE
• THE PERIODIC TABLE
• PROPERTIES OF MATTER
• SIMPLE MACHINES
• SOUND
800-843-3620
Teacher’s Guide and Program Copyright 1999 by Schlessinger Media,
a division of Library Video Company
P.O. Box 580, Wynnewood, PA 19096 • 800-843-3620
Executive Producers: Andrew Schlessinger & Tracy Mitchell
Programs produced and directed by First Light Pictures, Inc.
All rights reserved
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S
tudents in grade 5–8 classrooms possess a wide range of
b a ck ground know l e d ge . Student response to this video
program is sure to be va ried, so the teachers at these grades
need all the help they can get! This guide has been designed
to help the 5–8 science teacher by providing a brief synopsis of the pro gra m , p rev i ewing and fo l l ow-up questions,
activities, vo c ab u l a ry and additional resources.
Before Viewing: E x t e n s i ve re s e a rch tells how important
it is for the teacher to discover what the students know —
or think they know — about a topic, befo re actually starting a new unit.Therefo re , after prompting discussion with
the pre - v i ewing questions, lead your class to create a
“Everything We Think We Know About…” list.You may also
wish to preview key vo c abulary wo rd s , and have students
raise additional questions they hope will be answered.
After Viewing: Have your students share video excerpts
that fascinated or surprised them, then challenge your students to prove or disprove the accuracy of the facts they
put on their “ E ve rything We Think We Know About…” list.
Discuss what else they learned and use the fo l l ow-up questions and activities to inspire further discussion. E n c o u rage
students to re s e a rch the topic further with the Internet and
reading re s o u rces provided.
P rogram Summary
Friction is defined as a fo rce that opposes motion between two surfaces in contact.This resistance between surfaces depends upon two
factors: how much pressure is pushing them together and how uneven
the surfaces of the objects are.While some surfaces (bowling alleys) are
smoother than others (grave l - filled roads), f rom a microscopic point of
view, all surfaces are uneven.
One type of friction is sliding fri c t i o n . When two objects slide against
e a ch other, their uneven surfaces actually grind together, p roducing a
great deal of friction. Because of this fri c t i o n , we can walk on a pavement without slipping off.Another type, rolling friction, happens when
two surfaces come in contact only at a certain point as one object rolls
over the other without sliding. Fluid friction occurs when at least one
of the surfaces is a fluid, l i ke water or air. The shape of a boat, a plane
or a car is designed in a way to cut down on the wind or water re s i stance, there by reducing fluid friction. Lubricants are also fre q u e n t ly
used to reduce the amount of friction between two surfaces.
Scientists use the Greek letter µ (mu) to express the amount of friction
b e t ween surfa c e s . R u bber and asphalt (car tires and the road) have a
high mu factor, while ice and polished wood have a low mu factor. In a
hands-on demonstra t i o n , students conduct a test to gauge the amount
of sliding and rolling friction between diffe rent surfaces. One last kind
of friction is also explored — static friction.When objects are touching
without motion, they have static friction. Fortunately, when we sit on a
chair, the fo rce of static friction keeps us from slipping off on to the
floor. Friction always creates heat, w h i ch , l i ke friction itself, can either
be very helpful or problematic.
µ (mu) — (Also called the coefficient of friction) The Greek letter used
to re p resent the amount of friction between two specific surfaces.The
greater the friction produced, the higher the mu factor.
lubricant — A substance that is used to reduce friction in moving
parts. Motor oil is used as a lubricant in cars to reduce friction in
engines.
wind resistance — Also called drag; the name for fluid friction
b e t ween air and a moving object. Cars, planes and boats that are
designed with an aerodynamic shape reduce wind resistance or drag.
static friction — The fo rce that opposes the motion of two objects
that are at rest.
13. Where does fluid friction take place in a row boat? A jet plane? A
car?
14. What is µ (mu)?
15. What are some examples of substances with a high mu factor?
Low mu factor?
16. What are some examples of lubricants?
17. How do lubricants reduce friction?
18. What is static friction?
19. How does friction cause things to heat up?
20. When is the heat caused by friction helpful? When is it harmful?
Follow-up Discussion
P re-viewing Discussion
B e fo re students generate their list of “ E ve rything We Think We Know
About…” for this topic, s t i mulate and focus their thinking by ra i s i n g
these questions so that their list will better reflect the key ideas in this
show:
1. What is friction?
2. How does friction help us in our everyday lives?
3. What are some ways in which we ove rcome friction when it is
problematic?
After the class has completed their “ E ve rything We Think We Know
About…” list, ask them what other questions they have that they hope
will be answe red during this program. H ave students listen cl o s e ly to
learn if everything on their class list is accurate and to hear if any of
their own questions are answered.
Vocabulary
Focus Questions
The following words are included for teacher reference or for use with
students. They are listed in the order in which they appear in the
video.
friction — The resisting fo rce that opposes motion between two
objects that are in contact with each other.
sliding friction — The friction that results from two surfaces sliding
across each other, due to the grinding or rubbing that takes place.
rolling friction — The friction that results from two surfaces coming
in contact at a specific point, w h e re one rolls over the other without
sliding. Less fo rce is needed to ove rcome rolling friction than sliding
friction because less surface area is in contact.
ball bearings — Round materials often used between the wheel and
the axle of a ve h i cle in order to decrease sliding friction by increasing
rolling friction.
fluid friction — The friction that results when at least one of the two
surfaces that come in contact is a fluid like water or air. (Continued)
1. What is friction?
2. What are some examples of friction occurring in everyday life?
3. What are the factors that determine the amount of friction between
two surfaces?
4. Why are even smooth surfaces uneven on a microscopic level?
5. What is sliding friction?
6. W hy does sliding friction invo l ve more friction than the other
types?
7. What are some ways in which sliding friction is beneficial to us?
8. What is rolling friction?
9. W hy does rolling friction usually invo l ve less friction than sliding
friction?
10. What are ball bearings? Where and why are they used?
11. Why is the amount of a tire’s inflation important?
12. What is a fluid? What is fluid friction?
(Continued)
2
3
Research indicates that students will retain their previous misconceptions about a topic, in pre fe rence to new information, until they
a c t i ve ly recognize and correct their own errors. T h e re fo re, it is
important to have your students re - examine the facts/beliefs they
put on their “ E ve rything We Think We Know About…” list. It might
also be helpful to review the list by marking each entry with a “+” or
“-” to show which facts were correct and which were incorrect.
Discussions that ensue from thought-provoking questions provide a
good way to assess the ove rall depth of student understanding. The
following are some suggested discussion questions.
1. Discuss the fact that the rougher an object is, the more surfa c e
a rea it has. Smooth objects have less surface area, and there fo re
less friction. Relate this to the ridges on our hands known as fingerprints.
2. Talk about the fact that when two things rub toge t h e r, friction
takes energy of motion and conve rts it to heat. Explain how this
can be a help and a hindrance.
3. C o m p a re the wind resistance ex p e rienced by a large moving va n
and a sleek race car.
4. Ask students to explain why bicycles are easier to pedal when
their tires are fully pumped up with air.
Follow-up Activities
• H ave students rub their dry hands together rapidly to create a lot of
f riction and observe the heat produced.Then have them put lotion
on their hands and rub them together again, noting any differences.
In small groups, have them research different mach i n e s , looking for
ways that lubricants are used to reduce friction.
(Continued)
4