Our Earth in Motion
Understanding Time, Tides
and Seasons
2006
21 minutes
Program Synopsis
Why does the sun rise in the east? Why does the
moon change shape? How do tides happen? This
program explains in detail how the Earth and the
Moon move with respect to each other and the Sun,
why we have day and night and different time
zones. Why we have four seasons every year, two
tides and the different phases of the moon. This
program will enhance student understanding of key
concepts that are effectively demonstrated through
clear graphics and animation.
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Our Earth in Motion:
Understanding Time, Tides and Seasons
Teacher Notes:
Jeannette Jolley
B.Sc. (La Trobe University) B.Ed. (La Trobe University)
Introduction
The program starts by showing how the position of the Sun and the Earth’s rotation on its axis once every 24
hours gives us day and night, sunrise in the east, sunset in the west, and the 24 different time zones around the
world.
Because the Earth's axis is tilted at 23o and the Earth revolves around the sun once every 365¼ days, the two
hemispheres are facing towards the sun at different times of the year, giving us the seasons.
The Moon revolves around the Earth once every 29 days, and because we can only see the part of the moon that
is lit by the sun, we see the phases of new moon, first quarter, full moon and last quarter over these 29 days.
The tides are due to the gravitational pull of the Moon and the Sun on the earth’s oceans. The oceans are pulled
towards these large bodies, particularly towards the Moon because it is closer. Because the Earth spins on its axis
once every day, we experience daily changes to the depth of the oceans when that part of the Earth is pointed
towards the Moon.
Program Rationale
The program is aimed at lower secondary students (may be suitable for upper primary too) to help them
understand how the Earth and Moon move with respect to each other and to the Sun, why we have day and night
and so the different time zones, why we have four seasons every year, two tides and the different phases of the
moon.
Background Information
The Sun is the centre of our solar system, with the nine planets revolving around it in various elliptical orbits. The
Earth is the third planet out from the sun. Most planets have smaller bodies, natural satellites called moons that
revolve around them. The Earth has one natural satellite called the moon, which has no light of its own. We only
see the moon because it reflects light from the sun back to us. It takes 29 days for the moon to complete one
revolution around the Earth. The Earth spins on its axis once in 24 hours, and this axis is tilted at 23½o from the
vertical. It takes the Earth 365¼ days to complete one revolution around the sun. This is the length of one year.
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
DVD Timeline
00:00:00
Introduction
00:00:54
Day and Night
00:07:14
Seasons
00:11:47
Phases of the Moon
00:15:38
Tides
00:20:57
Credits
00:21:30
End program
Program Worksheet
Before the Program
1.
Initiate a class discussion on the cycles of day & night, the tides, the monthly cycle of the moon’s phases and
the yearly changes in the seasons.
2.
Find an aboriginal dreamtime story relating to these concepts and read it to the class to stimulate discussion
or kick off some research.
3.
Ask the students to research some dreamtime stories and write a summary about how the story tries to
explain the storyteller’s experiences.
4.
Ask the students to record the phases of the moon several times per week over a month. They could also
record some times of sunset and/ or sunrise and compare it to the times given in the daily newspapers. They
could note the places on the horizon where the sun rises or sets and compare this over a period of time.
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
During the Program
1.
Exactly how long does it take for the Earth to spin once on its axis?
_______________________________________________________________________________
2.
The axis is an imaginary line that passes through which two points on the Earth?
_______________________________________________________________________________
3.
How long exactly does it take the Earth to revolve around the Sun once?
_______________________________________________________________________________
4.
What do we call the time when the Earth rotates and the first rays of sunlight fall on a particular place?
_______________________________________________________________________________
5.
If the sun is high overhead here in the middle of the day, what would you expect to be the situation on the
other side of the Earth?
_______________________________________________________________________________
6.
What part of Australia sees the sun first at the beginning of each day?
_______________________________________________________________________________
7.
How many different times zones are there in the world?
_______________________________________________________________________________
8.
How many different time zones are there in Australia?
_______________________________________________________________________________
9.
Who came up with the idea of time zones and when was this?
_______________________________________________________________________________
10. What invention made it necessary for different places to have the same time?
_______________________________________________________________________________
11. In which country of the world is Greenwich?
_______________________________________________________________________________
12. What longitude would you expect to see given for Greenwich on a map?
_______________________________________________________________________________
13. What time would it be for astronauts out in space at this moment when they are constantly passing over many
different time zones?
_______________________________________________________________________________
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
14. About how many degrees is the Earth’s axis tilted from the vertical?
_______________________________________________________________________________
15. Which hemisphere is pointing towards the Sun in late December?
_______________________________________________________________________________
16. What season will this be in the northern hemisphere?
_______________________________________________________________________________
17. What two places on Earth can experience 24 hours of daylight in summer and 24 hours of darkness in
winter?
_______________________________________________________________________________
_______________________________________________________________________________
18. When is the winter solstice in Australia?
_______________________________________________________________________________
19. What is the name of the line drawn to show the most southerly distance the sun can reach from the equator in
June?
_______________________________________________________________________________
20. In which months do the two equinoxes occur?
_______________________________________________________________________________
_______________________________________________________________________________
21. What two seasons do we have when it is an equinox?
_______________________________________________________________________________
_______________________________________________________________________________
22. What is the shape of the moon’s orbit around the Earth?
_______________________________________________________________________________
23. How many days does it take the moon to complete one orbit?
_______________________________________________________________________________
24. What phase of the moon do we have when the moon is on the opposite side of the Earth to the sun?
_______________________________________________________________________________
25. How many days are there between a full moon and a new moon?
_______________________________________________________________________________
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
26. When we have had a new moon and so the moon appears to get bigger every day, do we say that the moon
is waxing or waning?
_______________________________________________________________________________
27. The force that pulls on the oceans to form the tides is called a
pull.
28. How many high tides does each place have in one day?
_______________________________________________________________________________
29. The high tides that are experienced when both the Sun and Moon are on the same side as the earth are
called
tides.
30. What do people living on the coast see when it is a neap tide?
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
After the Program
1.
Wordsearch: The letters that remain, once you have found all the words below, spell out a sentence if written
down in the order they are listed from top to bottom.
ANTARCTIC
ARCTIC
AUTUMN
AXIS
DARKNESS
DAYLIGHT
EARTH
EQUATOR
EQUINOX
GRAVITATIONAL
GREENWICH
HEMISPHERE
ILLUMINATION
LATITUDE
LONGITUDE
MOON
NEAP
PHASE
REVOLVE
ROTATE
SEASON
SOLSTICE
SPRING
SUMMER
SUN
TIDES
TILT
TIMEZONE
WANING
WAXING
WINTER
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Hidden Sentence:
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© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
2.
Student-created Crossword: Instructions to student:
Write meanings for any 10 words listed above, then make them into an interlocking crossword where your
meanings become the clues. Swap with a friend and see if you can solve each other’s puzzles.
3.
Expert Groups: Instruction to teacher
Divide the class into 5 equally sized groups (5 groups of 5 students is ideal) Give each group one of the
topics listed below to become very familiar with, so that they can teach the principle to others.
Topics:
•
•
•
•
•
Day & night
Time zones
Seasons
Phases of the Moon
Tides
Each group should spend 15-20 minutes preparing some basic notes and selecting suitable balls, which the
teacher has provided, to represent the Earth and Moon, and a torch or other light source to represent the sun.
After 15-20 minutes the groups should break up and form new groups so that each group has someone in it
who has become an ‘expert’ in that topic. This could be done in a second lesson. The experts now in turn
teach the new group what they have learnt in their original group. If each ‘expert’ takes about 10 minutes to
teach their topic, then this part of the lesson will take about 50 minutes.
If the class is smaller than 25, the first two topics could be combined creating only 4 topics. If one group has
more than 4 people, it could be organized so that in these groups two students share the first large topic and
break it into two as written above.
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
Suggested Student Responses
During the Program
1.
Exactly how long does it take for the Earth to spin once on its axis?
23 hrs 56 mins
2.
The axis is an imaginary line that passes through which two points on the Earth?
North and south poles
3.
How long exactly does it take the Earth to revolve around the Sun once?
365¼ days
4.
What do we call the time when the Earth rotates and the first rays of sunlight fall on a particular place?
Sunrise
5.
If the sun is high overhead here in the middle of the day, what would you expect to be the situation on the
other side of the Earth?
Night time, darkness or midnight
6.
What part of Australia sees the sun first at the beginning of each day?
East coast
7.
How many different times zones are there in the world?
24
8.
How many different time zones are there in Australia?
3
9.
Who came up with the idea of time zones and when was this?
Canadian Sir Sanford Fleming in 1878
10. What invention made it necessary for different places to have the same time?
Railways
11. In which country of the world is Greenwich?
England
12. What longitude would you expect to see given for Greenwich on a map?
0
13. What time would it be for astronauts out in space at this moment when they are constantly passing over many
different time zones?
Greenwich Mean Time (GMT)
14. About how many degrees is the Earth’s axis tilted from the vertical?
23
15. Which hemisphere is pointing towards the Sun in late December?
Southern
16. What season will this be in the northern hemisphere?
Winter
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
17. What two places on Earth can experience 24 hours of daylight in summer and 24 hours of darkness in
winter?
Places inside the Artic and Antarctic circles
18. When is the winter solstice in Australia?
June 22
19. What is the name of the line drawn to show the most southerly distance the sun can reach from the equator in
June?
Tropic of Capricorn
20. In which months do the two equinoxes occur?
March and September
21. What two seasons do we have when it is an equinox?
Spring and autumn
22. What is the shape of the moon’s orbit around the Earth?
Ellipse or oval shape
23. How many days does it take the moon to complete one orbit?
29
24. What phase of the moon do we have when the moon is on the opposite side of the Earth to the sun?
Full moon
25. How many days are there between a full moon and a new moon?
14
26. When we have had a new moon and so the moon appears to get bigger every day, do we say that the moon
is waxing or waning?
Waxing
27. The force that pulls on the oceans to form the tides is called a gravitational pull.
28. How many high tides does each place have in one day?
2
29. The high tides that are experienced when both the Sun and Moon are on the same side as the earth are
called spring tides.
30. What do people living on the coast see when it is a neap tide?
A smaller difference in heights between high and low tides
© Copyright Video Education America
Our Earth in Motion:
Understanding Time, Tides and Seasons
After the Program
4.
Wordsearch: The letters that remain, once you have found all the words below, spell out a sentence if written
down in the order they are listed from top to bottom.
G
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Hidden Sentence:
_T_ _H_ _E_
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