1. Seasons Change Happens
Do you like to make a pile of leaves and jump into them in the fall? Have you heard them crunch under your feet when you walk through them?
Let's explore the changes as they occur on earth. You will learn more about the seasons on Earth. Through this Unit, you will learn about earth's path around the sun and how it is related to seasons.
Seasons

2. What do you KNOW about seasons?
Before we begin, write a paragraph about what you already know about why earth has seasons. If you have questions, include them in your paragraph.

3. The Big Idea
Students will understand how Earth’s tilt on its axis changes the length of daylight and creates the seasons.
Let’s look at the BIG IDEA about Seasons.

4. Objective 1: Describe the relationship between the tilt of Earth's axis and its yearly orbit around the sun.
Describe the yearly revolution (orbit) of Earth around the sun.
Explain that Earth's axis is tilted relative to its yearly orbit around the sun.
Investigate the relationship between the amount of heat absorbed and the angle to the light source.
These are the State Objectives that you will be tested on at the end of the year. By the end of the Unit you should be able to explain each objective.

5. Objective 2: Explain how the relationship between the tilt of Earth's axis and its yearly orbit around the sun produces the seasons.
Compare Earth’s position in relationship to the sun during each season.
Compare the hours of daylight and illustrate the angle that the sun's rays strikes the surface of Earth during summer, fall, winter, and spring in the Northern Hemisphere.
Use collected data to compare patterns relating to seasonal daylight changes.
Use a drawing and/or model to explain that changes in the angle at which light from the sun strikes Earth, and the length of daylight, determine seasonal differences in the amount of energy received.
Use a model to explain why the seasons are reversed in the Northern and Southern Hemispheres.

6. A regular change in temperature that repeats itself every year
Seasons
A regular change in temperature that repeats itself every year
Let’s start by taking some notes on important words to know.

7. Words to know:
Axis - imaginary line around which Earth spins, causing day and night, and that is drawn from the north geographic pole through Earth to the south geographic pole

8. Words to know:
Rotation - spinning of Earth on its axis, which causes day and night; it takes 24 hours for Earth to complete one rotation

9. Words to know:
Revolution - the motion of Earth around the Sun, which takes about 365 1/4 days, or one year, to complete

10. Orbit - curved path followed by Earth as it moves around the Sun
Words to know:
Orbit - curved path followed by Earth as it moves around the Sun

11.
The following video uses a model to demonstrate Earth revolving around the sun. The tilt of Earth on its axis (see model) shows how seasons happen.
Remember that the sun is the center of our solar system. Like the other planets, Earth revolves around the sun. Earth takes one trip around the sun once each year. Ever wonder why we have a leap year?
Activity #1
Materials:
Globe
Tape
Electric light with a single bulb
Dark room
Procedure:
Place a straight line of tape on the globe between the north and south poles.
Turn on the light bulb.
Move the globe around the light bulb - make sure you keep the same side of the globe always facing the sun.
Demonstrate one year by moving the globe once around the light bulb.
Have the students demonstrate the earth’s revolution by standing in a circle and moving once around the sun (teacher standing in center).
Review: Now, write a follow-up paragraph about what you observed and how your ideas have changed.

12. The Earth's axis is tilted by 23.5°
The Earth’s Tilt
The Earth's axis is tilted by 23.5°
Let’s review what the video talked about.
The Earth is tilted 23.5 degrees and this causes the Earth to have seasons.

13. As the Earth moves around the Sun, this axis stays always pointing in the same direction.
Read Slide

14. This means that, during part of the year, the northern part of the Earth will lean more directly to the sun, and during other parts of the year the southern part of the Earth will.
Read Slide

15. The Earth during one full year as you would see it if you looked straight at it from the Sun.
Read Slide and watch the earth rotate.

16. The part of the Earth that is directly facing the sun changes with the time of the year.
Read Slide and watch the earth rotate.

17. The northern half faces the sun for a while, then moves south of the equator, only to move back to the north again.
Read Slide and watch the earth rotate.

18. Seasons - Changing Day Length
Notice that earth's axis is tilted. When it appears on one side of the sun, the light is stronger in the northern hemisphere. Then when the earth rotates so that the opposite side faces the sun, the light is stronger in the southern hemisphere.
Your goal is to determine how earth's tilt is related to the difference in light strength.
Pass out Activity #2 Worksheet instructions on this activity to the students.
Activity
Materials:
Globe
Masking tape
Pen or pencil
Bright flashlight or single bulb lamp
Procedure:
Start by numbering the tape from one to twenty four. Leave space between each number so you can tear the tape apart.
Place one piece of tape on each of the longitude lines (going from north to south) which intersect with the latitude line that goes through the United States near Utah.
Have a friend hold the light back so it shines on most of the globe.
The light represents the sun.
Tilt the globe so the North Pole is facing the light. Each number represents a one-hour division on the earth. Slowly turn the globe and see how many of the numbers can be seen at the same time.
Record your observations in your science journal.
Now tilt the globe so the North Pole is facing away from the light. Slowly turn the globe and see how many numbers can be seen at the same time.
Analysis:
1. When are the most hours visible in the northern hemisphere:
When the North Pole faces the sun or when the South Pole faces the sun?
2. Is there ever a time when the North Pole is always receiving sunlight?
3. Choose a country in the northern hemisphere and another country in the southern hemisphere. Make a graph or graphic organizer that compares the amount of daylight hours each of these countries experience during summer and winter seasons.

19. When the northern hemisphere is leaning toward the sun, the rays coming from it hit this part of the Earth at a larger angle than on other parts of the world.
Read Slide

20. This means that the same amount of light is distributed over a smaller surface, and so these places receive more heat than the others.
Read Slide

21. The southern hemisphere is experiencing Winter, the northern hemisphere has Summer.
Read Slide

22. The energy that hits the Earth by the Sun changes over the year.
The angle the Sun is above the horizon determines how much heat and light strike each square meter of ground.
Read Slide

23. In the winter the Sun's energy is weakened because the Sun's ray strike the ground rather indirectly as compared to the summer months when the Sun's rays strike the ground more directly.
Read Slide

24. Go to this Website for Instructions on assignment #3
This means that the ground receives more energy (more heat) per square meter in the summer than in the winter. 
More energy is received by the ground during the summer (high temperatures) and less energy during the winter (lower temperatures).
Go to this Website for Instructions on assignment #3
Read Slide
Assignment #3 – go to link on page
Materials:
Thermometer
Black paper
Overhead projector
Purpose: You will show that the amount of heat energy absorbed is related to the angle of the light source.
Background: Light is a form of energy that can cause object to increase in temperature. Have you ever noticed it is easier to get warmed by the sun's rays when the sun is directly overhead than when it is setting?
Procedure 1:
Take a piece of black paper and fold it in half.
Place a thermometer inside the folded paper.
Place your folded paper directly in front of projector lens in a vertical position as shown in the left photograph.
Record the temperature as you begin.
Record the temperature again after the light has been shining on the paper for two minutes.
Let the paper and thermometer cool to room temperature (about five minutes).
Repeat the same procedure holding the paper at a 45-degree angle or greater as shown in the right photograph.
Procedure 2:
Take a piece of black paper large enough to cover the overhead projector.
Cut a hole that is about 1/2-inch square in the middle of the paper as shown at the right.
Place the projector about one meter (about 36 inches) from wall. The projector should be facing directly at the wall as shown in Example 1.
Measure the area of the light square projected on the wall.
Move the projector so it is at an angle of at least 45 degrees to the wall. The projector will be at an angle to the wall as shown in Example 2 below.
Move projector so it is one meter (or 36 inches) from the wall.
Measure the area of this square.
Optional: Tape black paper on a board. Shine a flashlight, directly on the paper. Outline the lighted area with chalk or white crayon.
Angle the flashlight at 45 degrees and outline the lighted area with chalk or a white crayon.
Analysis:
In Procedure 1, what difference exists between the temperatures after two minutes with the two angles? Which example represents winter in Utah? Why?
In Procedure 2, how does the angle of the light affect the size of the area measured? Which example represents winter in Utah? Why?

25. Seasons - I'm Spinning and I Can't Stop!
Activity #4 Please click on the link below
You are to use a model to demonstrate earth revolving around the sun. The tilt of earth in your model shows how seasons happen.
Remember that the sun is the center of our solar system. Like the other planets, the earth revolves around the sun.
Remember: The earth takes one trip around the sun once each year.

26. Activity #5 Worksheet Sunrise, Sunset
Hand out worksheet #5: Sunrise, Sunset
Directions: Your goal will be to use collected data and compare patterns of seasonal daylight changes. Student Information: To solve problems scientists usually go through the same process. First, they develop a good answer to the problem they are working on (hypothesis), and then data needs to be collected in a controlled procedure or acquired from a reliable source. Data is often organized in a table or chart to aid in analysis of the information.
Procedure:
Look closely at the data table below. It shows the rising and setting times of the sun in St. George.

27. Activity #6 Worksheet Changing Shadows
Hand out worksheet #6: Changing Shadows
Description: Your goal will be to collect data and compare patterns of seasonal daylight.
Student Information: Remember that scientists do the same process. First you need to develop a good guess about the answer to the problem (hypothesis). Next you need to collect data in a reliable method. Organize your data in table or chart.

28. So, seasons are caused the tilt of the Earth’s axis
Review Time: Further explain each slide as a review

29. Remember: The seasons are the result of this tilt of the Earth's axis.
If the tilt of the Earth's axis was 0° there would be no difference in how the rays from the sun hit its different regions, and there would be no seasons.

30. The Earth's seasons are not caused by the differences in the distance from the Sun throughout the year.

31. The seasons are the result of the tilt of the Earth's axis.
I know this is a repeat, but it is important that you understand this idea. Many Americans, including Harvard graduates, do not know what causes seasons!
Review Time: Further explain each slide as a review

32. Review Look closely at where the Sun is hitting the Earth during each season:
Review Time: Further explain each slide as a review
Pay close attention to the tilt and what season it is.

33. Review Time: Further explain each slide as a review
******Pay close attention to the tilt and what season it is.*****
This one is the opposite direction – we want the students to understand that the tilt toward the sun determines it is summer.

34. Review Time: Further explain each slide as a review
******Pay close attention to the tilt and what season it is.*****
This one is the opposite direction – we want the students to understand that the tilt toward the sun determines it is summer.

35. Imagine Earth as it revolves around the sun
Imagine Earth as it revolves around the sun. The table below shows Earth at opposite sides of the sun. These two examples represent Earth's position for summer and winter.
Example A
Example B
Say: Previously you saw how Earth's tilt affected day length. Remember how the globe is tilted? Now we will look closely at how Earth's tilt and revolution around the sun are changing what season we have on earth!
Read Slide and discuss the two examples
Ask these Questions
Analysis: Click a link to see if you are correct.
Is Example A a demonstration of summer or winter in Utah?
Is Example B a demonstration of summer or winter in Utah?
Does the northern part of Earth get warmer when it is facing towards or away from the sun? Does Example A or Example B show winter in the southern hemisphere?
Write an explanation how the seasons of the Northern and Southern hemispheres are related.

36. Congratulations we have finished this Unit
Make sure you study for the test using the study guide
Pass out study guide reading packet