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| Investigating
Shadows Related Subjects: Science, Visual & Performing Arts, Mathematics Grades: 3-5 Medium: Drawing Author: Reuben H. Fleet Science Center Education Department Class time required: Two to three 50-minute class sessions  read/post
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 In this two-session lesson, students investigate the properties of shadows. Through a series of hands-on activities, they will become familiar with the formation of shadows and understand that the shape and length of shadows are dependent upon the position of the light source. In Part One, students discover how the angle of a light source affects an object’s shadow. In Part Two, they explore multiple light sources and the distance between the object and the light source. back to top   • Flashlights • White paper or graph paper • Objects of different shapes and sizes (blocks, balls, corks, fruit, action figures, etc.) • Measuring tapes or rulers (optional) • Glossary terms: angle, ray, shadow, variable • Background for the Teacher (PDF, Size: 20KB) • Images Online Materials
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• Read Background for the Teacher (PDF, Size: 20KB) to familiarize yourself with the scientific concepts behind this lesson. • Students will need to be assigned to groups of approximately four students each. • Print the above image onto an overhead transparency Session Two: • Students need to project their shadows onto a “screen” of white paper. You can either find space on a wall for each group to attach an 8” X 11” piece of paper or clip the paper to stiff cardboard and prop it up against a stack of books. back to top 
Session One: Introduction to Shadows 1. Start a class discussion to find out what students already know about shadows. Where have you seen shadows? What causes a shadow? Do shadows always look the same? 2. Give each group of four students a flashlight, a piece of white paper, and an object. Give the students approximately 5-10 minutes to explore and investigate shadows using these items. 3. After 5-10 minutes, have each group report their observations and discoveries to the rest of the class. Record each group’s ideas on the board or chart paper. 4. Challenge the students to think about what controls the length of an object’s shadow or what causes it to move from one place to another. Have you ever noticed that your shadow looks longer or shorter at different times of the day? 5. Pass out four additional sheets of white paper (or graph paper) to each group. Explain that they will now experiment with the position of the flashlight above the object. 6. Have the students place a piece of paper under their object and shine the flashlight directly over the top of the object. They should use a pencil to trace this shadow on the paper and label it “overhead”. 7. Have them place the object on a new piece of paper and increase the angle of the light source by moving the flashlight slightly downward, toward the surface of the table. Have them trace the shadow and label this paper “angle 1” (or other appropriate label). 8. Have the students repeat these steps three more times while continuing to increase the angle of the flashlight until the light is eventually perpendicular to the object. Be sure to have the students trace the outline of the shadow at each stage and label the shadows “angle 2 …3…4”. You may also want students to shade in the darker and lighter areas of each shadow accordingly. 9. When the groups of students have finished, ask them to put their traced shadows in order from “overhead” to “angle 4” and look for any trends. Ask them to look at the shortest and longest shadows. What was the position of the light when these shadows were made? 10. Have each group come up with a “rule” that explains how the angle of the light source affects the length or type of shadow produced. If needed, allow the groups to use their materials again to test their rule. Have each group share their ideas and discuss the findings as a class. Session Two: More About Shadows 1. Begin with a review of the previous lesson. Remind students of how the angle of the light source affected the length of the shadow. Challenge them to think about how the distance between an object and a light source might affect the shape of the shadow. 2. Give each group several pieces of paper, an object and a flashlight. (Note: the students will project the shadows onto the white paper “screen” – they will need to attach the paper to a wall or prop it up.) 3. Give the groups 5-10 minutes to investigate on their own. Ask them to experiment with the distance between the light and the object (move the light closer to or farther from the object) and the distance between the object and the screen (move the object closer to or farther from the screen). After a few minutes, give each group an additional flashlight and ask them to explore what happens to the shadow when they shine more than one light source on the object. 4. After 5-10 minutes have the groups share their findings. When was the object the clearest? When was it the fuzziest? Did you notice anything about the size of the shadow? What happened when you used more than one flashlight? 5. Explain that the students will now choose a variable to investigate in the next activity. Remind students why it is important to change only one variable of an experiment at a time. 6. Have each group choose from one of the following investigations: a) The distance between the object and the screen. b) The distance between the light source and the object. c) The number of light sources. 7. Each group should place their object on a flat surface and shine the flashlight behind the object so that it projects on the paper. They should trace and shade in the shadows of their object. (The students will need to use a new piece of paper for each shadow.) 8. Groups investigating the distance between the object and the screen should begin with the object close to the screen and move it progressively farther away (5 cm at a time works well). They should measure each distance and use this information to label each shadow. 9. Groups investigating the distance between the light source and the object should begin with the light source close to the object and move it progressively farther away (approximately 5 cm each time). They should record each distance and use this information to label their shadows. 10. Groups investigating the number of light sources should begin with one light source and then add additional sources one at a time (up to three flashlights). They should label each shadow according to the number of flashlights. 11. When the groups are finished, ask each group to present its findings to the rest of the class. 12. Ask students what other questions they have about light. Record these questions on chart paper for future investigations. Extensions, Session One Mathematics: Have the students measure the length of each of their traced shadows and make a graph comparing the angle of the flashlight and the length of the shadow. Mathematics: Have the students measure or trace their own shadows outside during different times of the day. Compare these results to those in the flashlight activity. Visual Arts: Show the students the artwork by Juan Sanchez Cotan and discuss where the light source is in the painting and its angle. Choose one or more of the objects from the above activity. Place the object in the center of the room so all of the students can see it. Turn off all of the lights and position a flashlight so that it creates a shadow. Hand out a piece of white construction paper and a pencil. Have the students complete a still life of the object, paying particular attention to the shades of gray in the shadow. Extensions, Session Two English-Language Arts: Have groups prepare a poster explaining the outcomes of their investigations and give presentations to the rest of the class (or another class). Mathematics: Have students measure the heights of the shadows they created. Make a graph using 2-D coordinate grids of shadow size vs. distance. Science: Have students design and perform additional experiments based on their questions about light and shadows. Hold a “Light Fair” to showcase their results. back to top  • Remind students to turn off the flashlights when not in use. • If there are not enough flashlights for groups to conduct the multiple light source investigation, this portion of the lesson can be done as a demonstration or class activity. • If the students have difficulty measuring distance, pre-mark the desired distances on the rulers using pieces of colored tape. back to top  CA Content Standards Third Grade Science 2a Light has a source and travels in a direction. Sunlight can be blocked to create shadows. 5c Use numerical data in describing and comparing objects, events, and measurements. 5d Predict the outcome of a simple investigation and compare the result with the prediction. 5e Collect data in an investigation and analyze those data to develop a logical conclusion. Fourth Grade Science: 6b Measure and estimate the weight, length, or volume of objects. 6c Formulate and justify predictions based on cause-and-effect relationships. 6e Construct and interpret graphs from measurements. Fifth Grade Science: 6b Develop a testable question. 6d Identify the dependent and controlled variables in an investigation. Third Grade Visual Arts: 1.5 Identify and describe elements of art in works of art, emphasizing line, color, shape/form, texture, space, and value. Fourth Grade Visual Arts: 1.5.1 Describe and analyze the elements of art (color, shape/form, line, texture, space and value), emphasizing form, as they are used in works of art and found in the environment. 2.1 Use shading (value) to transform a two-dimensional shape into what appears to be a three-dimensional form (e.g., circle to sphere). Fifth Grade Visual Arts: 1.3 Use their knowledge of all the elements of art to describe similarities and differences in works of art and in the environment. Third Grade Mathematics: 1.1 Choose the appropriate tools and units (metric and U.S.) and estimate and measure the length, liquid volume, and weight/mass of given objects. 2.3 Use a variety of methods, such as words, numbers, symbols, charts, graphs, tables, diagrams, and models, to explain mathematical reasoning. 3.0 Students move beyond a particular problem by generalizing to other situations. Fourth Grade Mathematics: 2.0 Students use two-dimensional coordinate grids to represent points and graph lines and simple figures. 1.0 Students organize, represent, and interpret numerical and categorical data and clearly communicate their findings. 2.3 Use a variety of methods, such as words, numbers, symbols, charts, graphs, tables, diagrams, and models, to explain mathematical reasoning. 3.0 Students move beyond a particular problem by generalizing to other situations. Fifth Grade Mathematics: 1.0 Students display, analyze, compare, and interpret different data sets, including data sets of different sizes. 2.3 Use a variety of methods, such as words, numbers, symbols, charts, graphs, tables, diagrams, and models, to explain mathematical reasoning. 3.0 Students move beyond a particular problem by generalizing to other situations. back to top  Teachers Rutgers University List of elementary school science lesson plans. A to Z Teacher Stuff List of elementary school science lesson plans on the subject of shadows and light. Students Holderness, Jackie. What is a Shadow? Brookfield, Conn: Copper Beech Books, 2002 Gibbons, Gail. Sun up, Sun down. San Diego: Harcourt, Brace, Jovanovich, 1983. Murphy, Bryan. Experiments with Light. Princeton: Two-Can Publishing, 2001 Rosinsky, Natalie M. Light: shadows, mirrors, and rainbows. Minneapolis, Minn: Picture Window Books, 2003 Tompert, Ann. Nothing Sticks like a Shadow. Boston: Houghton Mifflin, 1984. Zubrowski, Bernie. Mirrors: Finding out about the properties of light. New York: Morrow Junior Books, 1992 BBC School Wonderful interactive where students can explore the effects of light and shadow. There is also a small quiz at the end. back to top |
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Quince, Cabbage, Melon, and Cucumber Juan Sánchez Cotán |
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