What causes night and day?

NATIONAL SCIENCE STANDARDS:
Content Standard A: Science As Inquiry
Content Standard D: Objects In The Sky – Changes In Earth and Sky

This Activity demonstrates that the Earth’s rotation is why we have day and night.

*NOTE: Educators/Parents should consider reading the entire text to their children, if necessary, as they assist the child with the activity.

This is what we already know is true:
• Twenty-four hours equals one day and night on Earth.
• Most places on Earth have some amount of day and night every 24 hours.
• It always looks like the sun moves to make our day turn into night.
• Scientists know day and night is really created by the Earth turning.

ACTIVITY FOR STUDENTS IN KINDERGARTEN

1. Stick a small piece of masking tape onto the United States (or your own country) on the globe.
   
2. Draw a person on the tape. A stick figure is fine. This person represents you.
   
3. Turn on your flashlight. Darken the room. The flashlight represents the sun.
   
4. Hold the flashlight on the right side of the globe. Point the flashlight at the globe. Turn the globe until the light touches the masking tape person on the globe. This means you and your country are in daylight.
   
5. Slowly turn the globe. Notice the masking tape person (you) turns and moves out of the light. This means the person on the masking tape cannot see the sun and is in night.
   
6. Complete Worksheet A.
   

FOLLOW-UP DISCUSSION:

Ask the students to tell you (and show you, if necessary) what causes day and night. This will allow you to immediately know if they understand that the Earth’s rotation (not the sun moving) causes day and night.

ACTIVITY FOR STUDENTS IN GRADES ONE AND TWO

*NOTE: Conduct the Kindergarten Activity before you begin this Activity.

PART ONE

1. Move the masking tape person on the globe to the North Pole.
   
2. Hold the flashlight above the North Pole. Shine the flashlight directly down onto the masking tape person (you). NOTE: We know the sun is never actually directly over the North Pole. The flashlight’s position above the North Pole is just so we can compare the North and South Poles and daylight.
   
3. Slowly turn the globe. Compare the way the Earth globe turns you (on the masking tape) at the North Pole to how you moved in the first Investigation.
   
4. Complete Worksheet B.
   

FOLLOW-UP DISCUSSION:

Discuss with students what would happen today and tonight if someone lived at the South Pole when the sun is shining on the North Pole. Allow them to place the same masking tape person on the South Pole.

PART TWO

1. Allow the masking tape person (you) to remain at the North Pole.
   
2. Hold the flashlight level on the side of the globe and let it shine toward the masking tape person.
   
3. Slowly turn the globe. Compare the way the globe turns you (on the masking tape) to what happened when the flashlight was directly above the North Pole.
   
4. Complete Worksheet C.
   

FOLLOW-UP DISCUSSION:

Point out to students the fact that globes are tilted. This tilt causes different locations on the Earth to have different amounts of day and night during the year. Allow the students to turn the globe such that the North Pole is tilted away from the flashlight (sun). Discuss with them what happens to the amount of time the masking tape person stays in the light as the globe slowly turns.

EXTENSION ACTIVITIES FOR ALL GRADE LEVELS

We need to make sure we clear up some misconceptions from the News Break Video. A misconception is something that is believed to be true because we are taught it is true. For example, some students near the ocean believe the sky is blue because it reflects the ocean water. We know the sky IS blue but not from reflecting water. Believing it is blue is not the misconception – believing it is blue by reflecting the ocean water is the misconception they were most likely taught to believe.

The News Break Video presented many things that are not correct as shown. We will discuss each point and allow you a chance to find out what’s wrong in the picture. You can use books, the Internet, parents and other family members to help you find the correct answers and information.

1. IN THE NEWS BREAK VIDEO, the sky is a yellowish color.
What color is “normal” for the sky?

2. IN THE NEWS BREAK VIDEO, the stars in space are pointed.
What is a star’s true shape?

3. IN THE NEWS BREAK VIDEO, the color of space is blue.
What color is “normal” for space?

4. IN THE NEWS BREAK VIDEO, the sun and Earth are very close together.
What is the distance they are actually apart?

KINDERGARTEN - WORKSHEET A

Set up your materials to look like this drawing:

1. Turn the globe so that your Masking Tape Person is closest to your flashlight. That means you are directly beside the light. If you were really standing on this spot on Earth, where would you look to see the sun?

2. What part of the day (or about what time) is it when the sun is highest in the sky?

3. How far must you turn the globe to place the Masking Tape Person on the opposite side of Earth from the flashlight?

GRADES ONE and TWO - WORKSHEET B

Set up your materials to look like this drawing:

1. REMEMBER: The sun is NEVER really in a direct line with the North Pole.
   
2. Slowly turn the globe. When does the Masking Tape Person move into darkness?
   

Set up your materials to look like this drawing:



3. Place the Masking Tape Person on the SOUTH Pole (Antarctica). Keep the flashlight above the North Pole. Slowly turn the globe. When would the Masking Tape Person move into daylight?
   

GRADES ONE and TWO - WORKSHEET C

Set up your materials to look like this drawing:

1. This is where the sun is really located compared to the Earth – NOT above the North Pole.
   
2. Slowly turn the globe. Does the Masking Tape Person ever move into a part of globe that is dark?
   

Set up your materials to look like this drawing:



3. This is how the Earth tilts compared to the sun six months later (on December 21st).
   
4. Slowly turn the globe. Does the Masking Tape Person ever move into a part of globe that has light?