Planet Earth
A Yakima WATERS 5E Lesson
Introduction
This lesson will introduce students to Earth in space and some of the basic components of our
solar system: Earth a planet, orbiting the sun, a star.
This lesson is targeted to 5th grade students, but is suitable for 4-5 and can easily be enhanced
for 6-7 grades with the addition of tilt and seasons, forces of gravity, and movement of the
whole solar system. The lesson is planned for 1:15 hour.
Standards (being introduced)
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EARTH SCIENCE 4-5 ES1A Earth is approximately spherical.
EARTH SCIENCE 4-5 ES1B The earth spins relative to the sun and is the reason why earth
experience’s night and day.
EARTH SCIENCE 4-5 ES1C The earth travels about the sun in a nearly circular orbit. This orbit
is why we see different constellations at different times of the year.
Standards (being reviewed)

EARTH SCIENCE 4-5 ES1D The sun is a star
Outcomes
Knowledge:
● Explain that night and day is the result of the earth spinning relative to the sun
● Describe the Earth’s orbit around the sun as nearly circular
● Site that different constellations are visible at different times of the year as evidence of
Earth’s orbit
● Students describe the process of answering big scientific questions as a process that often
takes a long time and that many scientists help to answer the same or related questions
Skill:
-Students can demonstrate how the Earth’s spin creates night and day on Earth
-Students create a timeline that gives perspective and some historical context to the major
early astronomy discoveries
Materials and Equipment



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White Boards – one per student (if you don’t have these, a piece of paper will work)
Erasers and white board pens – one per student (again, pencil is fine)
Eratosthenes demonstration model (thick paper or poster board with two obelisks or pillars
(1 at Alexandria, 1 at Syene Egypt)
Flashlight or lamp – 1 for demonstration purposes


Medium sized sphere – 1 for demonstration; styrofoam, rubber, wood are fine. A crafts
store should have inexpensive styrofoam globes (Michaels)
Images of earth in space and of the sun (power point attached, handouts would work too)
Prior Knowledge
Students will be able to reference stars, the sun, and night and day from their own lives. They
will probably have heard that the Earth is round, but this is most likely the first time they will
learn that the earth is round, is a planet that spins and orbits the sun, a star. The lesson is
meant to be a gentle introduction into space science.
This lesson should follow a lesson that introduces students to gravity and that the Earth exerts a
force of gravity. The lesson I am teaching to prep for this lesson will teach students that planets,
stars, and moon can have different forces of gravity. Gravity is an important part of the
explanation in this lesson, but it would be possible to combine the explanation with gravity into
a later lesson if you like.
Safety
There are not any major safety concerns with this lesson. Psychological challenges may arise if
students are very unfamiliar with the concept of a round Earth and outer space. Assure the
children that they are safe even though our planet is spinning and orbiting a big ball of gas,
called the sun.
Engage (~3min)
Start by asking the students to imagine that they are far, far above the earth; way out in space,
looking down at Earth. “Imagine what Earth looks like? What shape is it? What color?” Today
we have very good technology that allows people to take pictures of the Earth from outer space
(show examples of images), but many hundreds of years ago people did not have the same
technology, yet they figured out that the Earth was round.
Explore: Part 1 (15 min)
Using powerpoint for visual assistance tell the students the a story about Aristotle and some of
his observations as to why the Earth is a sphere and not flat.
Many years ago, more than 2600 years ago, there lived a philosopher named Aristotle.
In those days philosophers were like scientists today. They study the world around them, making
observations and hypothesis. The developed experiments to test their hypothesis Aristotle
studied under another very well known philosopher and scientist, Plato. At this time many
people believed the Earth was flat. Plato taught that the Earth was round, but his student
Aristotle is better known for making important observations that were considered evidence for a
round Earth. One observation was that people who lived to the North could see different
constellations that people who lived off to the South. He concluded that this was only possible
for a curved surface. Another observation was that during a lunar eclipse, when the Earth
moved between the sun and the moon, the shadow across the moon is curved like a sphere.
Thus the Earth must be a sphere.
Activity:
Students, now I want each of you to act like you were a scientist going to school with
Aristotle. Can you show with a drawing or using a piece of paper that in different places in the
Earth difference constellations would be visible as Aristotle observed? You may draw a picture
on your white board or try to demonstrate this using a piece of paper (~2-5 minutes, the
students attempt something, but this may be very difficult).
Have students move on to explore the following questions. Students will work at different
paces, and some may want to spend more time trying to re-create Aristotle’s observations.
What are some things that are different between flat and curved surfaces? Can you use
those differences to test if the Earth’s surface is flat or curved? How would you try to prove that
the Earth Is round?
The goal here is for students to practice thinking scientifically, asking questions, and thinking
about observations that can be tested or used as evidence of something. Students will probably
come up with the idea that on a round surface objects will roll off. This is true, but remind them
about gravity (this can be complicated, they may need to be reminded that we people are small
compared to the Earth and that only over distances is the curvature of the Earth evident). Some
students may note that when you look out at the horizon, it appears to curve just a little. They
may mention that the phases of the moon show a curve just like the lunar eclipse. They may
also reference TV shows or things family members had told them or lessons from 4 th grade.
Explain (10 min)
Have some students (1-2 or 3 if there is a variety of ideas) share with the class how they
drew/demonstrated Aristotle’s ideas.
Review the accurate and inaccurate components of their ideas. With the whole class, go over
Aristotle’s ideas explaining them and paying extra attention to common confusions you
observed among students during the exercise.
In their science note books, have students record:
● Ideas (their own, a classmates, or from your presentation) about a flat Earth compared to a
spherical Earth
● Aristotle’s two important observations they lead him to believe the Earth was round
(The writing typically takes more time than expected, jump right to it asking students to write
down ideas as the class is discussing them)
● Start a timeline in their science notebooks that can stretch across two pages, and place
Aristotle towards the left hand side (demonstrate on board) Students will continue to add
names to the time line throughout the lesson to help them see how the science in developed
over time, by many people
Explore: Part 2 (5mins)
About 50 years after Aristotle, another scientist and philosopher, Eratosthenes made
another important observation that proved the Earth was round. He had heard that in
Alexandria, a city in what is today the North of Egypt, the sun was directly overhead at noon on
the summer solstice. At this time, no shadows where cast. He knew that is Syene, a city in
southern Egypt, there were shadows at noon on the summer solstice. Being a scientist he set out
to see for himself if there truly were no shadows at noon on the summer solstice in Alexandria
and if so, why not?
Students, I would like a volunteer to come up to the front of the classroom and using this
model show how there could be a shadow at Syene but not shadow at Alexandria (may need to
take 2 to 3 volunteers, depending on success rate).
Demonstrate that on the flat surface the two obelisks will either both have shadows, or both
not have shadows BUT on a curved surface there may be a shadow in one place, and no shadow
in the other place.
Explain (10 min)
Gravity! (2min)
This scientists were correct! The Earth is a sphere. It took a very long time for people to all
agree about this, even though Aristotle and Eratosthenes had evidence. There was evidence
that the Earth was round, but that still not explain why the Earth was round. It turns out that
gravity is the major factor for why the Earth is a sphere. Remember that gravity is an attractive
force – it pulls things in. Any object has some very minor gravity, but a huge object like the
Earth has a lot of gravity. Earth’s gravity is strong enough to keep you, and me, and all the
buildings in the world secure on the ground. It turns out that Earth gravity, which is strongest at
the very center, pulls everything nearby into its center. Everything wants to get as close as it
can to the center because the gravity is pulling very hard. As a result the Earth is a sphere. Any
point on the surface of the Earth is about as close to the center of the Earth as any other point
on the surface of the Earth (draw a diagram to help show this using a circle and showing the
equidistant radii connecting the center of the circle to any point along the circumference). The
Earth might have started out a little lumpy, but over time gravity has shaped it into a sphere!
Class Discussion (8min)
Facilitate a discussion with the students to review the ideas of Aristotle and Eratosthenes. Use
the following questions to guide the discussion (if particular questions arose during the
activities address them now; likewise if students are confused about one major idea spend
more time on that) To start, ask if there are questions.
-What did Aristotle use as evidence that the Earth was round?
The difference in constellations from north to south and the shadow of the Earth during a lunar
eclipse.
-Were these observations easy to test?
Constellations generally yes, but clear skies are needed, multiple observations and you must
travel north to south to see the difference. The lunar eclipse is not easy to test, because they are
rare and short lived. Any bad weather could botch everything up. Also, the complexities of a
Lunar eclipse were not well understood by many people at that time and even today many
people are not familiar with why they happen.
-What did Eratosthenes use as evidence that the Earth was round?
The difference in shadow between Alexandria, no shadow at noon on the summer solstice and
Syene, shadow at noon on the solstice.
-Were his ideas easy to test?
Generally speaking yes. Time may have been a challenge to tell, and he needed to travel a
distance between the places. Would take at least a year to check because he can only be in one
place at a time.
-What are some things that would make it difficult to test Aristotle and Eratosthenes’ ideas?
Lunar eclipse is rare. Keeping accurate time to test shadows in different places. Cloudy skies.
In their science notebooks have students add Eratosthenes to their timeline.
Extend/Elaborate (25 min)
Now the students will transition from the questions, evidence, and understanding of the Earth
being round to applying that new knowledge to better understand normal phenomena such as
day and night. The difference between day and night may have been mentioned, but this is the
time to discuss why we experience day and night on Earth.
Raise your hand if you think the Earth is round.
(Should all raise their hands)
Raise your hand if you learned about new evidence that proves the Earth is round.
(Should mostly raise their hands – generally some act like they knew everything)
Raise your hand if you know why we experience night and day on Earth.
(There will probably some who aren’t totally sure. This is not meant to start a
discussion, but for you to assess and to help the students transition into the next
ideas being presented)
Raise your hand if you think that right now the Earth is moving.
(Again, this is for assessment and transition)
Can you feel the Earth moving?
(This question is to get their minds ticking)
How do you KNOW that the Earth moves?
(This is an important step –“how do we know what we know” – Students should
have enough time to being to ponder this idea, but not too much. Go right ahead
into the story so that they don’t get discouraged if they cannot explain how and
why they know something)
Students, we are going to think about some of the ideas and questions that scientists asked
once they knew the Earth was indeed a sphere. Remember that a good scientist continues to ask
questions and when she or he discovers answers, often more questions can be ask based on
those answers!
In the 1500s, nearly 2000 years after Aristotle and Eratosthenes lived, most people knew
that the Earth was a sphere. An important question that scientist were trying to understand was
how does the sphere, Earth, behave? Is it stationary? Does is move? If so, how does Earth move?
Many observations had been made about stars, the sun, and other planets and all of these
indicate movement. But not every scientist agreed about what the answers were to these
important questions. The most important question being, “Is there something at the center of
our universe (what we call our solar system today) and if there is something at the center what
is? Do all other objects revolve around the same center?
Activity:
Students, on your white board, I want you to draw what you think the basics solar
system looks like. Please label what you put at the center of the solar system. If you are not
sure, take a guess! (2min)
This is quick assessment of what the students know and give them the
opportunity to think about the relationship of the Earth and Sun before you tell them.
Be sure to announce that the sun is at the center of our solar system, in case any students did
not know that. Draw a diagram on the board that shows the sun at the center. (Ask the students
how the Earth moves around the sun, some may have already drawn this on their white boards)
and draw the circular orbit of the Earth (do your best to make it good circle with the sun in the
center!)
The realization that the Earth is a sphere is deeply connected with the idea that the Earth
spins and that night a day are the result of Earth spinning, rather than the result of the sun
circling the Earth. Before anyone knew the Earth was round, people believed that the sun moved
across the sky, as we see from morning to night. When scientists found that the Earth was round
most still believed the sun circled around the Earth causing night and day. When scientists first
introduced the idea that the sun was stationary and the Earth moved around the sun it was a
really big deal! If the sun did not revolve around the Earth, then the Earth would need to spin in
order for there to be night and day!
Demonstrate with the flashlight a ball the rotation of the Earth. The sun (flashlight or lamp)
only shines on part of the sphere at a time, giving daylight in some places and nighttime in
other places. Be sure to properly demonstrate that there is an imaginary axis about which the
Earth spins and verbally share this with the students (5min)
For many years scientist did not know that the sun was at the center of the solar system.
The first known scientist to mention the possibility that the sun was stationary and that the
Earth revolved around the sun was Aristarchus of Samos around the same time as Eratosthenes.
Aristarchus found that the Sun was at least 6 to 7 times larger than the Earth and it would make
more sense for the small object to be moving that for the larger object to be moving. His papers
were lost, and the scientist who is considered the first to demonstrate that the sun was
stationary and that the Earth revolved around the sun is Nicolaus Copernicus, who published his
mathematical model in 1543. He used observations of relative movements of other planets and
the stars in his calculations that all the planets circled the sun. More evidence came from the
fact that different constellations of stars are visible at different points of the year, indicating
that the Earth moves through different parts of space. Following his work Johannes Kepler
expanded on Copernicus’s ideas and Galileo Galilei used the first telescope to confirm
heliocentrism, a solar systems with the sun at the center. More recently, 1920s huge
advancements in technology, including the launch of the Hubble satellite among others, allowed
Edwin Hubble to identify our Galaxy, the Milky Way and discover that there are many galaxies in
the universe which was even larger than scientists had thought!
Explanation (3-5min)
Does anyone know why the Earth orbits around the sun?
Take 2 hands/ideas.
Gravity again! The Sun has an ever stronger force of gravity and the Earth is attracted to
it. The sun is a star, not a planet like Earth, but is still has mass and exerts a force of gravity. The
reason our Earth didn’t go flying right into the sun is because it is moving very fast and is also
pulled by the gravity of other things in space. The Earth speed of the Earth and the pull of the
suns gravity keep it moving in a circle around the Sun.
Have students return to their timeline and add Aristarchus, Copernicus, Keplar, Galileo and
Hubble. For fun, have the students indicate where they are (farthest right end = present) and
they can make up a fun hypothesis or next question for space science.
Continued Extension option (throughout the quarter/rest of the year)
In their science note books, have the students record some observations of the sky, night and
day, at home. They should include what the moon looks like, where in the sky is the moon (E v
W; high in the sky or near the horizon; visible at day or night or both, what constellations they
see and where, and if the sun always rises from the same place on the horizon (and anything
else they want to add). This is something that they can share with the class briefly on a
designated day (maybe first Friday of each month, nighttime observation share time)
Evaluate (0 min)
Collect the science note books and go through these for evaluations. There is a lot of
assessment throughout this lesson, and at each step the students should be writing the
important lessons down. Within the week, the material should be review and a brief quiz given,
but no formal assessment is necessary here.
Follow-up: As noted above, sharing their observations that they record at home will make a
good follow up activity that does not take too much time and can be tucked in the first or last 5
minutes of their science period.
Performance Rubrics
ES1A
Element
Knowledge
(1, 75%)
Skill (1,
25%)
ES1B
Element
Knowledge
(1, 75%)
Excellent
(4 pts)
Student is able to
identify that the
Earth is a sphere
and site 2 or more
points of evidence
supporting this
not including
photos (the
Earth’s shadow on
the moon is
curved, different
constellations are
visible in different
parts of sky from
different parts of
world, shadows
are cast
differently as the
same time in
different parts of
the world, curved
horizon)
Student can
accurately
demonstrate 1 on
the lines of
evidence that they
site for the Earth
being a sphere.
Excellent
(4 pts)
Student can
clearly explain
that the Earth
spins around an
invisible axis,
relative to the
sun, and that
night and day are
a result of this
Spin.
Good
(3 pts)
Student is able to
identify the sun as
a sphere and site 1
line of evidence
that support this
hypothesis not
including photos
from space (the
Earth’s shadow on
the moon is
curved, different
constellations are
visible in different
parts of sky from
different parts of
world, shadows
are cast differently
as the same time
in different parts
of the world,
curved horizon)
Developing
(2 pts)
The student
can identify
the Earth as a
sphere but
cannot site
evidence to
support this.
Minimal
(1 pts)
Student does not
identify the Earth
as a sphere, they
demonstrate
confusion
between the
Earth be flat,
curved or a
sphere.
No Participation
(0 pt)
Student is present
but does not
participate
whatsoever.
Student can
demonstrate
mostly accurately
one of the lines of
evidence they site
for the Earth being
a sphere.
Student
attempts to
demonstrate
something
showing the
Earth is a
sphere, but
can not
successfully
do so.
Student is
confused by the
process of
demonstrating
the Earth as a
sphere is does not
attempt to do so.
Student is present
but does not
participate.
Minimal
(1 pts)
Student cannot
explain that or if
the Earth moves
relative to
anything.
No Participation
(0 pt)
Student is present
but does not
participate
whatsoever.
Good
(3 pts)
Student can
explain that the
Earth spins
relative to the
sun and that
night and day
are a result of
this spin.
Developing
(2 pts)
Student explains
that the Earth
moves somehow
relative to the
sun and that
night and day are
related to the
movement.
Student may not
identify “spin” or
may not explain
that Earth motion
Skill (1,
25%)
ES1C
Element
Knowledge
(1, 5o%)
Skill (1,
50%)
Student can
accurately
demonstrate the
Earths spin
relative to the
sun (or light
source) and can
properly identify
when night or
day is present at
specific locations
on the model
Earth.
Student can
demonstrate
mostly
accurately the
Earth’s spin
relative to the
sun. They can
identify night or
day generally
on the model
Earth.
Excellent
(4 pts)
Student can
accurately
explain that the
Earth’s orbit
around the sun is
circular and site
the change is
constellations
visible at
different times of
the year as
evidence of Earth
orbit.
Student can
accurately depict
with sketch or
demonstrate
with model the
circular orbit of
the Earth around
the sun and site
the change is
constellations
visible at
different times of
the year as
evidence of Earth
orbit.
Good
(3 pts)
Student can
accurately
explain that
the Earth’s
orbits around
the sun is
circular.
Student can
accurately
depict with a
sketch or
demonstrate
with models
the nearly
circular orbit
of the Earth
around the
sun.
is relative to the
sun.
Student attempts
to demonstrate
movement of the
Earth but cannot
do so accurately
and/or cannot
indicate when
night or day take
place on the
model Earth.
Student is
confused by the
process of
demonstrating
the movement of
the Earth and
does not use the
model Earth at all.
Student is present
but does not
participate.
Developing
(2 pts)
Student can
explain that
the Earth
moves around
the sun but
indicates that
the motion is
non-circular
and/or
irregular.
Minimal
(1 pts)
Student cannot
explain that the Earth
orbits around the sun.
No Participation
(0 pt)
Student is present
but does not
participate
whatsoever.
The can depict
with a sketch
or demonstrate
with a model
that the Earth
moves around
the sun, but
cannot do so
accurately
(non-circular
orbit, irregular
orbit)
Student cannot
sketch or
demonstrate any type
of Earth orbit around
the sun. or Student
uses the wrong
objects in their
sketch/demonstration
and the wrong
relative motion (sun
around Earth, plant
around Earth etc.)
Student is present
but does not
participate.
Teacher Background Info
This lesson is interdisciplinary, using history as a background for understanding how early
scientists attacked complex questions. Thus, the teacher may want to consider where how this
lesson fits in with their history/social studies lessons and with their science curriculum. Because
this lesson uses story telling as the fundamental teaching tool, it is important that the teacher
be familiar with the stories and the names used. Practice will be necessary. The teacher must
be comfortable with the gravity, changing constellations over the year, fundamentals of our
solar system and know that our solar system is in the Milky Way, a galaxy among many others
in space.
Note: This lesson is designed for a class with a wide range of learning levels. If you class excels
in mathematics, there are some neat calculations that Eratosthenes etc. did that can be
recreated in class. I have also found that my class learns best if the lesson is segmented with
multiple short activities, rather than a more traditional longer activity and longer
discussion/explanation.
Reference Material
-Information on Eratosthenes: See Carl Sagan’s video that describes Eratosthenes observations
about the shadows at Alexandria and Syene. The model that I am using for this lesson is taken
from this video. (youtube link: http://www.youtube.com/watch?v=VnHn03QQ8lU)
-Any encyclopedia will provide a nice brief introduction to the philosophers mentioned in this
lesson. -Wikipedia provides a nice summary and some good images on its heliocentric page.
By: Meilani Bowman-Kamaha’o, Fall 2011, for Harrah Elementary School