A MOVING EXPERIENCE - FORCES AND INERTIA
Grades 5 - 6
In this lesson, the students will have the opportunity to consider
the first part of Newton's First Law of Motion, the Law of Inertia of objects
at rest, which states that every object remains at rest unless acted on
by a force. The video gives the students several examples to illustrate
the law of gravity and its consistency. Activities to correspond with and
extend the understanding of the concept of inertia include predicting and
then testing the action of balls of various weights and sizes being released
at a forty degree angle on an inclined plane, pulling paper out from under
a glass of water and other weights at different speeds, hitting a block
on the bottom of a stack of blocks, catching a coin on the elbow, and other
experiments to show the effect of various forces on objects. After doing
or watching these experiments, the students should be able to predict the
effect various forces have on objects that are originally at rest.
3-2-1 Classroom Contact: Motion and Forces: Play Ball (Children's
Students will be able to:
- identify and explain the first part of Newton's First Law of Motion
(also known as the Law of Inertia of objects at rest) that states that every
object remains at rest unless acted on by a force;
- use experimental materials to experience the law, first making predictions,
testing them, and writing out the results of their activities and their
observations of the experiments;
- extend their understanding to explain life situations like ski jumper's
skills or the force it takes to push a stalled car or to get a rocket ship
off the ground.
- chalk and blackboard or
- dry board and dry board markers
- glass with water
- file card
- ten coins
- pack of 8/5 x 11 in. paper
- bottle with a small mouth and neck
- rubber band
- six magazines
- heavy book
- sheets with directions for each activity group
- meter ramp
- balls of different sizes and weights
- target container to catch balls
- cotton string
- several sheets of paper
- one pencil
- inertia - an object's resistance to changing its velocity (in
our case, the resistance of an object at rest to moving)
- force - a push or a pull
- Newton's First Law, part one - every object remains at rest
unless acted upon by a force
- gravity - a force that objects have on each other
Have the students sit in groups of four and explain that during
this class they will be expected to do some individual work and writing,
and also some group work. Ask each group to choose a chairperson, a recorder,
a reporter and a hands-on worker. The chairperson's job will be to keep
the group on track and to lead the group work. Ask the hands-on worker to
come up to get a pencil and several sheets of paper for each member of the
Explain to the students that from the time people can talk, they always
ask why things happen. Scientists are people who devote their lives to asking
"why" and experimenting to find out the answers. Whenever we do
that, we are scientists, too. Say, "Isaac Newton was born in England
in 1642, about the time our American colonies were being founded. He started
asking "why" early in his life and he never stopped. One of the
things he wondered about and experimented with was motion - how and why
things moved. We are going to consider some of these questions today and
do some experiments to help us get a clearer idea of them."
Direct the students' attention to a demonstration area where all can see.
Place an index card on a glass of water. Put a coin on top of the card and
very quickly pull the card off the glass in a straight line. (The coin stays
in place, but without the card to hold it up, it falls into the water.)
Ask the students to write down individually what they saw and why they think
it happened that way.
After a few minutes, have the students within each group share what they
have written with the chairperson in charge. Their task is to come up with
a group explanation for what happened and why. The note taker takes this
When this is accomplished, have the reporters give the groups' responses.
Write them on the board and accept all responses.
The focus for viewing is a specific responsibility or task(s)
students are responsible for during or after watching the video to focus
and engage students' viewing attention. To give students a specific responsibility
while viewing, say, "When the video starts, you will see two students,
Stephanie and Lee, doing some experiments with motion. Watch to see if you
can see any connection between their experiments and what was going on with
the coin and the glass.
BEGIN the video with Stephanie sitting looking at a ball
on a table, just before she says, "Believe it or not, this is an experiment."
After Lee says, "...a different kind of force, gravity," PAUSE.
This will give the students time to think about the connection between the
coin and glass experiment and the experiments Stephanie and Lee did.
Ask the students to discuss the question in their groups. After a couple
minutes, let the groups' reporters share the gist of their groups' discussions.
The students should notice that gravity caused the coin to drop into the
glass when there was no card to support it. They will probably mention that
the card was pulled away so fast, the coin didn't have time to move with
Tell the students that they will now be watching a section of the video
showing examples of the gravitational force.They will need to watch for
five examples of gravity. RESUME the video. Lee says, "Our planet
is really grabby." PAUSE after Lee says, "...and it always
pulls with the same force." This will give the students time to list
the examples they have seen.
Say, "In each group, come up with five examples of gravity shown in
the video. Then add two more that your group can think up on your own. Recorders,
start writing." After a few minutes, have the reporters give their
lists and write them on the board, one column for the video examples, one
column for the new examples.
Tell the students that in the next segment, Stephanie and Lee prove a very
important property of gravity. Say, "Let's watch to see if we can learn
what this property is and how these young scientists prove it."
RESUME video with Stephanie saying, "So, gravity is something
we can depend on." PAUSE after she says, "That helps us
predict the movement of objects," to make sure the students understand
that gravity is a force that is consistent.
Say, "Discuss in your groups what Stephanie and Lee proved about gravity."
After a minute or so, ask the students to respond and discuss the consistency
Say, "Here's a problem for us to work on. In the video we saw the same
kind of ball shot through the hoops. What if we used different kinds of
balls - different weights and sizes. Would that affect the consistency of
Set up the ramp at a forty degree angle on a table or desk. It can be made
of such things as two meter sticks taped together, or of a portion of a
plastic rain gutter marked off to a meter's length, either leaning on a
pile of books or a storage box. Have the lower end of the ramp at the edge
of the table or desk. Have several balls - marbles, balls made of wood,
cork, metal, a ping-pong ball, a nerf ball, a baseball - on hand.
Say, "Will balls of different sizes and different weights land in different
places when released from the same spot on a ramp?" Ask for predictions.
Have the groups talk it over and then take a tally making a quick graph
on the board with columns saying Same Heavy Farther Heavy Closer or whatever
the students mention. Discuss the students' reasons for their predictions.
Release one ball from one meter's height. Place the target container on
that spot (or mark the spot with masking tape). Release all other balls
from exactly the same height and in exactly the same way. (This is a good
time for mentioning controlling variables in scientific experiments.)
The balls follow the same path and land in roughly the same place. The force
of gravity pulls each ball down he ramp at the same speed. The ball continues
to move forward as it falls. Occasionally a very light ball will encounter
air resistance like the proverbial feather which needs a vacuum to drop
at the same speed as a penny.
After the students have observed and discussed this experiment, have them
return to their seats and write up what happened: the question asked, will
balls of different sizes and weights land in different places when released
from the same spot on a ramp?, their original prediction, what they observed,
their conclusion based on the observation.
For the students who finish early, have this question posted on the board:
Why don't ski jumpers hit the same spot when they race down a steep ramp
into the air? Have them write the answers and then, when most students are
finished writing up the experiment, discuss the question.
Say, "After Newton observed some of the things we have observed, he
wrote them down, and some of his observations have been called 'laws' ever
since. We have experienced a couple examples of his First Law also called
the Law of Inertia.
"In Stephanie's first experiment, the ball stayed in the same spot
on the table. This illustrates the Law of Inertia for objects at rest which
states that every object remains at rest unless acted upon by a force. Why
was her experiment so boring? What could have happened to cause the inertia
of the ball to be broken?
"So, in the video, various forces were discussed. Lee showed how to
apply several kinds of force to a ball, and Stephanie showed how a different
kind of force called gravity also affects the inertia of an object. They
both proved that the force of gravity is consistent, and we proved that
gravity affects objects of various sizes and weights in the same way.
"Let's see how Stephanie and Lee conclude their experiments."
FAST FORWARD and BEGIN the video as Stephanie and Lee sit
looking at the ball on the table. Stephanie says, "Remember this experiment?"
Stop the video when Lee says, "...it's consistent and predictable."
Say, "We have a few more activities to do today that will
push our understanding of inertia and gravity a little farther."
Note to the teacher: Included are five activities for the students
to do as groups and a culminating activity to use with the whole class which
could be used as an assessment tool. Because of time constraints, these
could be done on another day. The last part of the video could be kept until
the end of the activities to bring closure to the whole process.
Each group will go to a work station and follow the instructions on the
sheet found there. The chairperson or reporter will read the instructions,
the hands-on person will be in charge of the experiment (the rest of the
group may need to assist, depending on the experiment), and the recorder
will write down the results on the sheet. The chairperson will be in charge
of asking the group to predict what will happen before actually doing the
Activity One: Brick on a String
Give students a brick with a string (one meter in length) tied around it.
The free end of the string will be tied to a rubber band. Place the brick
on a carpeted floor and pull on the rubber band. Watch very closely. What
Note to the teacher:The rubber band stretches until the brick starts
moving. As it is pulled further it stretches less because the initial inertia
of the brick has been overcome making it easier to keep the brick moving.
You might bring to the students' attention how hard it is to get a stalled
car moving by pushing it. Once its inertia is broken, however, it's easier
Activity Two: Move It Slowly
Give students several sheets of paper three inches wide and about eleven
inches long. Place one sheet near the edge of the table, with about four
inches extending over the edge. Put a bottle with a small mouth and neck
upside down on the paper near the edge of the table. Take a pencil and place
it in the loose end of the paper and carefully roll the paper around the
pencil. Keep rolling very slowly until the rolled paper gets to the mouth
of the bottle. Keep going. What happens? Why?
Note to the teacher: the paper will move out from under the bottle
because inertia tends to keep the bottle upright, right where it was to
begin with, so long as you move slowly and carefully.
Activity Three: Move It Out
Give students several sheets of paper and a heavy book. Place one of the
sheets on the edge of the table, and put the book on top. Grasp the edge
of the paper and pull it very quickly from the table. What happened to the
Note to the teacher: The book remains stationary because moving the
paper so quickly did not overcome the book's inertia.
Activity Four: Catch the Coin
Put several coins on the table. Place one coin on your elbow, holding your
arm outstretched, parallel to the floor with your hand open, near your face.
In one sudden, very quick move, drop your arm down and catch the coin. You
will have to practice a few times to get the knack. What's going on here?
Note to the teacher: the coin, being still, tends to remain in the
same position until gravity pulls it down. If you move very fast, you can
Activity Five: Grab the Mag
Take a stack of magazines. Have one of the magazines in the middle of the
stack stick out a little. Pull that magazine out very quickly. What happens?
Fix the stack again with one magazine sticking out. Pull it out slowly this
time. What happens? Why?
Note to the teacher: when the magazine is pulled out quickly, the
inertia of the magazines on top keeps them in the same position, but gravity
pulls them down. When the magazine is pulled out slowly, the force of the
pull has time to spread out to the magazines on top, overcoming their inertia
as well, and they move.
After the groups have an opportunity to do at least three of these activities
(in a classroom, they could be left out for students to experiment with
during specified times), conclude with a discussion of the results. The
groups will turn their sheets in with the names of the students in the group
There may be questions about moving objects and inertia, the second part
of Newton's First Law of Motion, and that's another whole lesson.
As assessment, or just a culminating activity, have the students go back
to individual seats and to their individual papers. Have several lengths
of cotton thread, about sixty centimeters each, on hand. Tie one end of
one thread to a broom handle and the other end to a block. Tie another thread
to the block, letting the end dangle freely. Have volunteers help hold the
broom handle about head height. Ask the students to predict which string
will break first when you pull on the dangling end.
First do it very quickly. What happens? Why?
Then retie the threads and do it very slowly. What happens? Why?
Students could write about this as individual assessment pieces, or the
class could discuss the experiment together.
- Invite a coach from a local high school to visit or send some of her/his
students over to discuss how they overcome inertia to pole vault, make baseballs,
footballs, etc. go where they want them to go, or run in a relay. There
may be many other examples to demonstrate how gravity always needs to be
taken into consideration when playing sports.
- Ask an auto mechanic to visit, or visit a garage, to have the person
explain what it takes to start a car moving (mechanically this time - not
with a push), and once it's running, how the mechanism changes.
- Ask a dance instructor to visit (especially if there are some of his/her
students in the class) to demonstrate how dancers do those graceful lifts
and other moves, taking inertia and gravity into account.
- Ask ice-skaters how they start.
- Ask gymnasts when they have to take gravity into consideration.
- Visit a high school or college physics lab to have an instructor demonstrate
the penny and the feather falling in a vacuum, or other examples of gravity.
Discuss what the class has been learning with their phys ed teacher, and
ask for suggestions for activities that demonstrate Newton's First Law.To
extend the ball throwing idea, show the rest of 3-2-1 Classroom Contact:
Play Ball to the class. The section where the softball pitcher demonstrates
putting spin on the ball, and the physics demonstrations connected with
it are very useful.
Conduct research on the world in the seventeenth and early eighteenth centuries
when Isaac Newton lived. How did his discoveries affect people's lives?
Read aloud the short biography about Isaac Newton entitled, "The Short
Giant," in Mathematicians are People Too by Reimer and Reimer
(Dale Seymour Publications). Have the students illustrate parts of Newton's
story to make a storybook of his life. Share the book with a younger grade.
Research the amount of force it takes to get a rocket ship off the ground.
Master Teacher: Mary Gene Devlin
Deerfield Elementary School, South Deerfield, MA
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