Procedure:

A. Have each group present to the whole class their responses to Item D in the Exploration above and their plan for providing evidence for their ideas. Help students communicate the results of their activities using possible observations to justify their conclusions. Help the students compare the results of each group’s plan for providing evidence.

B. With the Sun visible in the daytime sky, plan a short field trip to the school grounds. Give each group a large copy of Figure 1. Ask each student to make a sketch of the sky facing south and the horizon. Students are to draw in the location of the Sun and important objects visible on the horizon and their own location on the school grounds. This field trip can be completed in less than ten minutes. The activity should be repeated three to five times throughout the day, twice in the morning, once at noon, and twice in the afternoon. Each observation should be an hour apart. Record all observations on the same drawing. Each drawing of the Sun should include the time. Warn the students not to look directly at the Sun. Damage to the eye can occur in just a few seconds.

B. Write the key questions from the Exploration (part B) on the board. Ask the student groups to answer these questions based on their observations. Ask them to compare these answers to the answers they inferred during the exploration. Have them report their answers to the whole class.

C. Bring out and explain the discrepancies between the student inferences and the observations just made. It should be clear to the students that their original ideas could not be supported by evidence they have just gathered. During a brief discussion, ask them where they got their ideas about the Sun’s location and motion in the sky. How different were their original ideas from the observations they have made? The Sun never is overhead. The path of the Sun keeps it in the southern part of the sky all day long. During the fall and winter months, the Sun rises in the southeast, moves to a high position in the south, and sets in the southwest. As an additional assignment, some students may be asked to observe the location of sunrise on a weekend morning while others observe the late afternoon Sun and a third group observes the sunset. Providing students with a compass may help them with directions.

D. The following activity requires a clear day with a bright Sun. Obtain one globe for each group. The best type of globe to use in this activity is one that is detachable from its’ stand. Model how they are to use the globe when they go outside. Out of posterboard, ask each student group to cut a strip one inch wide and one foot long. Form it into a circle and staple the ends together. Demonstrate how to set up the globe in front of the students. Take the globe out of its stand and set it on the floor into the base formed by the posterboard circle (Figure 2). Put your city or town location on the exact top of the globe. Point the north pole of the globe toward the direction of north. Instruct the students to do the same with their globes when they go outside. Outside this activity should be done on blacktop or grass to reduce the glare of sunlight on the globe. Tell the students that with the Sun shining on the globe, this is exactly the way the Earth looks to an astronaut on the moon. He would see part of the Earth lit up by the Sun and other parts in shadow. He would also see where the day and night come together and the edge of the shadow. The shadow’s edge would occur on both sides of the Earth.

To demonstrate a method for students to determine the amount of sunlight any city receives during a day, ask the students to find places on the Earth at a specific latitude that are turning from night into day and day into night. This is the shadow’s edge. Count the number of longitude lines from the shadow’s edge on the right side of the earth around to the shadow’s edge on the left side of the Earth. These longitude lines generally are fifteen degrees apart. This is how much the Earth turns in one hour. If there are ten fifteen-degree intervals from one shadow’s edge to the other, then for that latitude there will be ten hours of daylight during a twenty-four hour period.

Before taking the students outside provide each group with a small lump of clay and a toothpick. Then give each group a sheet of paper with the following questions. Where is the Sun overhead right now on the Earth? How many hours of daylight exist for cities in the following latitudes: 50 degrees north? the latitude of your town? the equator? and 40 degrees south of the equator? Ask the students to explain and illustrate each group’s answers to these questions.

E. Return inside and have each group report its findings. Discuss these, adding information as necessary.

F. Closure: The Sun is overhead someplace on the Earth at any time. At night the Sun is overhead on the other side of the Earth someplace. The Sun is never overhead for any portion of the USA, except Hawaii. Cities on the Earth at different latitudes have differing amounts of daylight hours on most days of the year. Only on March 21 and September 21 are the days for every city on the Earth the same -- twelve hours of daylight. This can be seen on a globe outdoors on these days as the shadow’s edge lights up half of the Earth so that the shadow cuts exactly through the north and south poles. At other times the shadow’s edge falls to one side of the poles.

Evaluation: Each group should have a complete response to each question and illustrations that provide evidence to support their answers to each question. Assess students group skills by observing that they stay with their group while it is working and that pay attention to how much time they have to carry out each activity.

A. Give the students a handout containing the following directions and information.

B. As an extended expansion activity, have the students note the sunset and sunrise times over a two week period as reported in the newspaper and comment on the day-to-day changes in the times. The students should report their findings to the whole class.

C. Another extended expansion activity could involve the students in obtaining the sunrise and sunset times for the town’s latitude for an entire year. Students could be asked to record and graph the length of the daylight period on the first day of each month. The students should report their findings to the whole class.

D. Summarize the lesson by reviewing the activities and major findings of the various parts of the lesson.

Evaluation: Ask students draw the Sun’s path on Figure 1 during the day from sunrise to sunset. On a drawing of the Earth showing North and South America, ask the students to circle the area where the Sun is overhead at this time. On the same drawing of the Earth ask the students to indicate cities where the daylight hours today are the greatest and where they are the smallest.