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# Investigation 1 – Lab

### MINDSET

This Investigation is designed to:

• model the position of the Earth and the Sun during day and night,
• model the Earth’s tilt and the effect of the tilt on the seasons on Earth, and
• encourage you to conclude that although direction or angle of sunlight and distance from the Sun affects the temperature on Earth, the angle of sunlight has a greater impact on seasonal changes in temperature than distance.

### BE PREPARED

Student Preparation for the Investigation includes having students gather the following materials. This preparation takes place on lab day after student lab groups have settled at their assigned lab tables.

Note: The materials are listed inyour SDR. They are also listed below for your reference.

• (1) light bulb socket
• (1) student globe
• (1) 100 watt light bulb
• (1) small accessory box
• (1) lab marker
• (1) toothpick
• (1) metric ruler
• (1) light meter
• (1) calculator
• (1) roll of masking tape
• (1) meter stick
• (1) hot hands protector
• (2) pieces of clay approximately 1 cm3

Direct one student from each lab group to collect the materials listed in their SDRs.

### INVESTIGATE

• Briefly review rotation.
• Stand.
• Imagine that you are a planet that is rotating on its axes.
• Slowly rotate as a planet would rotate.

Note: Students should calmly spin in place.

• Briefly review revolution.
• Imagine that you are planets which is revolving around the sun.
• Imagine that the Sun is in the middle of your desk or table.
• Slowly revolve around the imaginary Sun.

• Do you think that the earth revolves or rotates?
• Yes, the Earth both revolves and rotates.
• Slowly model the motion of the earth as it revolves and rotates.

Note: You should slowly spin around while circling around your desk or table.

• Reflect on the PreLab video as you move through the procedural steps.
• During the Experiment, every procedural step is important. If one step is skipped, data can become invalid. To help you keep on track, read each step thoroughly, complete the step, then check it off (Read it – Do it – Check it).
• Complete all of the procedural steps in your SDR.

Note: The procedural steps are listed below for your reference.

1. Create a model of the Earth and the Sun.

A. Using a meter stick, mark the midpoint of the width of a lab table (around 36 cm) at least 60 cm from one of the two short table edges. Mark this point w/ a small piece of model clay.

B. Starting on the long edge of the table closest to you, place four 12 cm pieces of masking tape and label them “Spring N.H.”, “Winter N.H.”, “Summer N.H.”, and “Autumn N.H. as shown.

C. Place the small accessory box upside down over the clay.

D. Place the light socket with the 100 watt light bulb on the middle of the small accessory box.

2. In our solar system, the Earth’s axis of rotation is tilted at a 23.5° angle. To properly model the Earth, the globe must be tilted. Locate the white plastic circle on the bottom of the globe.

A. Tilt the globe so that the white circle is sitting within the circular stand on which the globe sits.

B. The white circle should be touching the inner edge of the stand so that the globe is tilted.

C. To help you visualize the Earth’s axis, place a piece of clay on the white circle on the top of the globe.

D. Place a toothpick in the clay so that the toothpick is straight in relation to the globe. This will place the toothpick at a tilt relative to the table.

Note: The axis of your globe should point in the same direction throughout the experiment.

3. Place the globe on the piece of tape labeled “Winter: Northern Hemisphere”.

A. The back of the globe’s plastic stand should touch the back edge of the tape.

B. The globe’s stand should now be approximately 20 cm from the light bulb.

C. Tilt the Earth away from the Sun and turn the globe so that North and South America are facing the Sun.

D. Note the direction in which the Earth is tilted. The Earth must remain tilted in this direction throughout the activity.

Trial 1: Model night and day on Earth.

1. Turn on the light bulb and observe how the light hits the globe. Rotate the globe on its axis one complete turn.

Note: Depending on the light distribution in your science lab, you may find it helpful to turn off some or all of the lights in the room. The more dimly lit your room, the more reliable your results will be.

1. When it is day in the United States, which countries are experiencing night? List three.

Trial 2: Model the position of Earth during the four seasons.

1. Keep the globe at its current position. In this position, it is Winter in the Northern Hemisphere.
2. Visually compare the amount of light received in the Southern Hemisphere versus the Northern Hemisphere.
1. In this position, does the Southern Hemisphere receive more light, less light, or an equal amount of light as the Northern Hemisphere? (circle one)

More           Less           Equal

1. Move the globe to the piece of tape labeled “Spring: Northern Hemisphere”. The back of the globe’s plastic stand should touch the back edge of the tape. The toothpick should be tilted in the same direction as it was in the previous position. In this position, it is Spring in the Northern Hemisphere.
2. Visually compare the amount of light received in the Southern Hemisphere versus the Northern Hemisphere.
1. In this position, does the Southern Hemisphere receive more light, less light, or an equal amount of light as the Northern Hemisphere? (circle one)

More           Less           Equal

1. Move the globe to the piece of tape labeled “Summer: Northern Hemisphere”. The back of the globe’s green stand should touch the back edge of the tape. The toothpick should be tilted in the same direction as it was in the previous position. In this position, it is Summer in the Northern Hemisphere.
1. In this position, does the Southern Hemisphere receive more light, less light, or an equal amount of light as the Northern Hemisphere? (circle one)

More           Less           Equal

1. Move the globe to the piece of tape labeled “Autumn: Northern Hemisphere”. The back of the globe’s stand should touch the back edge of the tape. The toothpick should be tilted in the same direction as it was in the previous position. In this position, it is Autumn in the Northern Hemisphere.
1. In this position, does the Southern Hemisphere receive more light, less light, or an equal amount of light as the Northern Hemisphere? (circle one)

More           Less           Equal

1. Record: Use the observations you recorded in the previous questions to determine the season the Southern Hemisphere would experience at each position. Record and explain your conclusions in the following table.

1. Place the globe at the position marked “Winter: Northern Hemisphere” with North and South America facing the light bulb.
2. Determine the intensity of light and heat from the sun that reaches Santiago, the capital of Chile, during the Northern Hemisphere’s winter season.

A. Place the light meter on top of Santiago.

B. Measure the number of light units reaching the light sensor.

C. Record: Collect data from three trials and record the data in Table B.

14. Determine the intensity of light and heat that reach Washington DC during the Northern Hemisphere’s winter season. The Sun’s light travels almost the same distance to reach Santiago as it does Washington DC.

A. Place the light meter on top of Washington DC.

B. Read the number of light units reaching the light sensor.

C. Record: Collect data from three trials and record the data in Table B.

Move the globe to the position marked “Summer: Northern Hemisphere”. Turn the globe on its axis so that Washington, D.C. and Santiago, Chili are facing the light. Determine the intensity of light that reaches Santiago and Washington D.C. from this position using the light meter. Record the data in Table B.

### CLEAN UP

Clean up your lab bench after your experiments are completed.