Prove Your World
Lesson Plans
GRAVITY
Grade Level: MS 6-8
NGSS
Motion and Stability: Forces and Interactions
Disciplinary Core Idea:
PS2.A: The motion of an object is determined by the sum
of the forces acting on it; if the total force on the object is not
zero, its motion will change. The greater the mass of the
object, the greater the force needed to achieve the same
change in motion. For any given object, a larger force
causes a large change in motion.
PS2.B: Gravitational forces are always attractive. There is a
gravitational force between any two masses, but it is very small
except when one or both of the objects have large mass.
Performance Expectations:
MS-PS2-4 Construct and present arguments using evidence
to support the claim that gravitational interactions are attractive
and depend on the masses of interacting objects.
MS-PS2-5 Conduct an investigation and evaluate the
experimental design to provide evidence that fields exist
between objects exerting forces on each other even though the
objects are not in contact.
Backward Design
Know
gravity
- The natural force of attraction between any two
massive bodies.
attraction – the ability of one object to be pulled by another
Understand
There is a gravitational force between all objects in the universe.
Fields exist between objects creating forces on each other even
when the objects do not touch each other.
Be Able To Do
Plan and carry out an investigation that demonstrates the
interactive characteristic of gravitational forces between masses.
Use the evidence from a planned investigation to demonstrate
the interactive characteristic of gravitational forces between
masses.
Essential Question
How can I demonstrate that forces exist between objects
that make them move without touching each other?
Objectives
1. Given a diagram of the Cavendish set up, students will
demonstrate an understanding of the interactive
characteristics of gravitational forces by labeling, illustrating
and interpreting all of the interactions with 90% accuracy.
2. Given a question about a real life situation, students will
demonstrate an understanding of the interactive
characteristics of gravitational forces between masses by
planning an investigation at a competent level as assessed
on the rubric.
Flow of Teaching and Learning
Experiences
ENGAGE (Estimated time 15 minutes)
Teacher gives each group of children two balls – one
tennis, one ping pong and poses the question:
What are the properties of each of these balls?
Allow time to explore the properties. Then ask:
Are these two balls attracted to each other?
Allow time for students to manipulate the objects and
answer the question with explanations.
2. Next the teacher asks:
What would happen if I rolled these balls off the
edge of the desk?
Teacher places the balls on the edge of the desk and
allows students to answer. Teacher asks children to
explain their ideas.
3. Teacher introduces her “friends” (in the video) who
have experienced similar ideas.
(Students are allowed to play with the balls on their
desks to explore properties and see if one can be
attracted to the other. They must impart reasonable
explanation for their thoughts.
Students watch the balls on the desk being used by
the teacher. They offer answers to the question along
with reasonable explanations.)
PLAY PART ONE OF THE PYW GRAVITY VIDEO
HERE
EXPLORE (Estimated time 60 minutes)
Room is set up in three stations. Materials at each
station are listed in steps one through three.
1.
Using materials provided (light rope, washers,
rocks of medium size, 2 inch diameter clay
balls, any other large, heavy materials,
yardstick, two desks or chairs to use as
suspension devices), the task is to find a way
for the students to demonstrate a larger mass
having an attraction on a smaller mass.
2.
Using materials provided (same materials as
above and any others that the students may
decide that they need), the task is for the
students to demonstrate a way for a larger
mass to have an effect on a smaller mass
WITHOUT having the two masses touch.
3.
Using materials provided (same materials as
above and any others that the students may
decide that they need), the task is to design an
experiment that will demonstrate two masses
being attracted to each other without either
mass touching the other.
NOTE: Throughout the student exploration, the
teacher should be moving from group to group
and asking leading questions that will help the
students develop their explorations. An
example might be: What would happen if you
put several heavy objects on one side of one
small object on a string?
4.
Students log all of their questions, procedures
and results in their journals.
5.
Teacher regroups the class and asks the
students to share in the experience of her
friends from PYW.
(Students rotate through the three tasks, numbers 1
through 3 above, in small groups of four. Whole class
works on one task at a time within their small groups.
Students keep individual journals of their questions,
procedures and results.)
PLAY PART TWO OF THE PYW GRAVITY VIDEO
HERE
EXPLAIN (Estimated time 20 minutes)
Teacher reconvenes students in their working groups
with directions to analyze their results from EXPLORE
activities in light of the PYW video.
Next the teacher shows the students the PYW Video
that explains the Cavendish investigation.
PLAY PART THREE OF THE PYW VIDEO HERE
The students are asked to present their findings to
the rest of the class and use either a poster they have
created, a computer presentation, or a creative
performance to explain their understandings in light of
their explorations and the information in the video.
(Students discuss their tasks in light of their learning
from their activities and the viewing of the video. They
create and present a poster, computer presentation,
or creative performance for the class that
demonstrates their group’s understanding of their
learning.)
EXTEND (Estimated time depends on direction of
student investigations)
PLAY PART FOUR OF THE PYW VIDEO HERE
Teacher states the following:
Our friends at PYW just gave us some ideas about
the attractive force of gravity. Select one of these
tasks or design an investigation of your own that
explores the attractive force of gravity.
Task One:
If everything with mass has gravity, then explore the
relationship between the moon and Earth. Consider
some of these questions: How does the moon’s
gravity affect the Earth and how does the Earth’s
gravity affect the moon? What would happen if the
moon did NOT have gravity? What would happen if
another moon orbited the Earth?
Task Two:
Some medical experiments are conducted in outer
space because the effects of gravity are greatly
reduced. This makes the research extremely
expensive. How would you design a special place on
Earth to reduce the effects of gravity so that this
research could take place ON the Earth?
EVALUATE (Estimated time 20 minutes)
The teacher allows the students to select their task
and/or she assigns one of the tasks to specific
students depending on the assessment of their needs.
1. Teacher gives students a diagram of a
Cavendish set up. Students are to use arrows,
added diagrams, words and/or pictures to
describe the forces at work.
(Students complete the given diagram to
demonstrate their understanding of the attractive
forces between objects.)
2. Students are given a question:
“How would you demonstrate to the school
principal that there is an attraction between her
coffee cup and her desk?”
(Students design their own demonstration of the
attractive forces between two common objects.)
Resources: PYW videos, light rope (like twine),
different kinds of balls (tennis and ping pong), small
washers, several large, heavy objects like bolts, rocks,
weights, student journals, colored pencils, yard,
meter sticks or dowels, chairs and desks.
Diagram of Cavendish model for EVALUATE activity.
Copyright PYW 2014
NAME__________________________ DATE________
Use arrows, words, or added diagrams to explain the
attractive forces between objects. Use colored pencils to
help you explain the forces.
copyright PYW 2014