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Sunrise...Sunset - Bilingual Telemation Unit K-3 Lesson 1:
The Shadow Knows...
Background:

The earth's axis is tilted at an angle of about 23.5 degrees, so the sun appears to be higher in the sky above the horizon during the summer and lower in the sky during the winter. The earth also leans in the same direction as it revolves around the sun. On July 4, the "aphelion," the earth is actually 3 million miles farther from the sun than it is during the winter, January 2, the "perihelion." Summer solstice - June 21, the longest day of the year; winter solstice - December 21, the shortest day of the year. On the vernal equinox - March 21, and autumnal equinox - September 23, the sun is directly above the equator and day and night are of equal length in all parts of the earth.)

Long ago people realized shadows moved as the sun moved. They realized that they could figure out where the sun was in the sky by observing shadows over time. The earth changes its place in space as the seasons progress. The sun's apparent path changes because of the earth's tilt. It appears higher above the horizon in summer and lower in winter.

Concept:

The shadow of an object in sunlight can be used to determine the position of the sun. Changes in the length of the shadow relate to important changes in the day and in the seasons of the year.

Purpose:

To demonstrate how the changes in the length of a shadow is affected by the apparent path of the sun. (Shorter in winter, longer in summer.)

Objectives:

Students will measure the shadow cast by a constant object (meter stick).

They will record and collect the data over time (over at least 1-2 months).

Students will use telecommunications to compare and contrast their data with other schools.

Inquiry Activities:

What causes your shadow to change in size at different times of the day?

Will the shadow be the same at all times of the year? Why?

Are shadows the same in every part of the world? Why?

How can shadows help you tell time?

Materials:

Story of Peter Pan

Meter Stick

Butcher paper (about 6' x 4')

Tape

Compass

Marker or crayon

Student activity sheets

Pre-Assessment:

Teacher Directions:

Using the Pre/Post-Assessment sheet, have the students draw where they think the shadow of the building should be for Picture A, B, and C. If appropriate, have the students write in the answer for the question about shadows.

Directed Lesson:

(In class)
Review/discuss the story of Peter Pan. Ask "What did Peter Pan lose in the Darling children's playroom? Can we lose our shadow also? What are shadows? What makes our shadow? Does it change?" Have students try LEP activity #1 below.

(Outside on the yard)
Allow students to predict the length and direction of their shadows during different times of the day (before recess, lunch, and dismissal). Ask "Is the size of your shadow different at different times of the day?"

Measuring the shadow of a meter stick:

  1. The students set a 6' x 4' (or larger) piece of butcher paper in a sunny area outside on the yard.

  2. Use a compass to find north and mark the letter N at the top center edge of the paper for north. Next turn the paper so that the N faces north.

  3. Hold the meter stick straight up at the bottom center edge of the paper (opposite the N). Ask: "If you are facing north, which direction will the sun travel across the sky?" (from right to left, east to west)

  4. Have the students trace and measure in centimeters (or use nonstandard units such as handspans, etc.) the length of the shadow cast by the meter stick. Mark the time and date on the butcher paper; record data on the student activity sheet.

  5. Measure (in units) and record the meter stick shadow's length daily at about the same time on the Student Data Sheets (copy enough sheets for the time you will be gathering data). Ask "Will the shadow be the same length next week? If we lived in Seattle or Mexico City, would the shadow's length be the same? Why or why not?"

  6. Continue data collecting and predicting the outcomes.

  7. Have students use telecommunication to share their results.

Teacher Tips:

This activity can be done as a whole class or small group activity (4-5 groups).

You will get the greatest amount of variation in length of shadow if you conduct this experiment in the fall or spring.

Set up the shadow stick near a familiar play yard landmark, such as the flag pole or near the ball box. It is important to keep the location constant.

Have a pair of student "shadow stick" monitors responsible to record the data daily. Each week, you can choose a new pair.

Copy enough weekly data sheets for the length of the activity.

Telecommunications:

Share the data your class gathers on the line with other schools using the following format:

  1. Teacher's Name
  2. School
  3. City
  4. State
  5. Date
  6. Time of Day
  7. Shadow Length (with unit of measurement)

Conclusion:

After a 1 - 2 month period, ask "What did we find out about the shadow of our stick? Why did it happen? How could we use shadows to help us tell the time?" (By observing the position of the shadow, we can begin to see a pattern where the shadow falls at different times of day, such as morning, noon, afternoon, night.)

Post-assessment:

Use the same pre/post assessment sheet to observe growth in understanding.

English Language Development Strategies for Limited English Proficient Students:

  1. Total Physical Response (TPR): Have students enact each other's shadow. Pair students to mirror each other's movements; play a simple version of Simon Says; use simple yes/ no types of questions for assessment.

  2. Role Play: Divide students in groups of 5-6. Have one student represent the sun, another student represents the building, and the rest represent the shadow of the building cast by the sun. Ask "If the sun moves across the sky, where would the shadow be?"

  3. Language Building Activity: Use an overhead projector and various flat objects. Secretly select an object and display it on the overhead. Have the students use different adjectives to describe the shadow and guess what it is.

Extensions:

Video:
Students tape shadows of various objects, then guess what the objects are.

Math:
Measure, estimate, record and graph shadows of different objects.

Social Studies:
Find out how different cultures used shadows to tell time (Egyptians, Romans, Greeks, etc.).

Language Arts:
Write class or individual poems about shadows. "Shadows are . . ."

Arts:
Students present a shadow play using flashlights and hands or cut-outs. Shadow dancing: students in pairs make identical parallel movements. Make profile drawings of students using a flashlight, white chalk, and black paper.

Make a shadow mask (like the one in the story "Shadows.")

Resources:

Laserdisc:

Windows on Science, by Optical Data
Primary Science 3, "Light around us" - basic concepts on shadows
Primary Science 2, "Using the sun to tell time" - sundials, shadow variations

Literature:

"Shadows," by Blaise Cendrars, MacMillan, 1982 (Grades 2-3. African folk tale about a shadow that acts like a human being. Rich vocabulary; Caldecott medal.)

"Shadows Are About," by Ann Whitford Paul, Scholastic (Grades K-2. Informative, great visuals.)

"What Makes Day and Night," by Franklyn Branley, Crowell, 1986 (Grades K-2. A must for primary science.)

Literature - Cultures:

Aesop's Fables, "The Dog and his Shadow" - deals with morals, greed.

Native American Stories, "How Grandmother Spider Stole the Sun" (Keepers of the Earth, by Joseph Bruchac, Fulcrum, 1989).

"El Teatro de las Sombras," by Michael Ende, grade 3-5. Elderly woman takes in stray homeless shadow, creates shadow (silhouette) theater.

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