Shadows and Light

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Shadows and Light
"... you can't paint sunlight, you can only paint
what it does with shadows on a wall. And what if
you're the wall? What if you never cast a shadow
or rainbow of your own, but have only caught
those cast by others?" -Wallace Stegner, The
Spectator Bird, 1976
stardate.org

• By Richard H. Audet
• Roger Williams University

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Shadows and LightFor the Teacher
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Lesson Overview
This is a two day lesson for grades 4-8.
Students are introduced to shadows, explore how
their shadow changes over the course of a day,
and use their understanding of shadows to build a
sundial. They are assessed by their explanation
of how a sundial enables someone to tell the time
of day.
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Instructional Goals

• Students will develop an understanding of how
  shadows form, how shadows change over the course
  of a day, and be able to explain the principles
  of how a sundial operates.

www.ncf.ca
5
Formative Assessment

• Students will be assessed on their ability to
  explain how a sundial can be used to tell the
  time of day.
• In their explanation, students will have to
  properly use all of the following terms
• Shadow Gnomon Sun
• Compass Light Compass

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Opening The Lesson

• Tracing a Shadow
• Show the Groundhog Day clip. What causes the
  groundhogs shadow to appear?
• Read Bear Shadow by Frank Asch. In this story,
  a bear attempts to escape a shadow that seems to
  be chasing him.
• Find out what students already know about
  shadows.
• What do you know about shadows that makes the
  book funny?
• Why did Bear's shadow disappear when he hid
  behind a tree?
• Why did the shadow disappear when he buried
  it?
• What makes a sun shadow fall one direction at
  one time and another direction earlier or later
  in the day?
• What other questions do you have about
  shadows?
• (Fromhttp//www.sciencenetlinks.com/lessons.cfm?B
  enchmarkID11DocID10)
• 4. What causes day and night? (The night sky is
  dark like a shadow because the suns light is not
  shining on the Earth. When its night time, its
  like were all in the Earths shadow!)
• 5. Review the Tracing a Shadow Activity with
  students (From http//troop851.ellenbecker.net/My
  20and20my20shadow.htm).

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Opening The Lesson
http//www.education-world.com/a_lesson/04/lp330-0
5.shtml
8
Developing The Lesson - 1

• Follow Your Shadow
• In this lesson, students investigate shadows and
  discover how the position of the sun and time of
  day affects a shadow. This lesson must be
  performed on a sunny day on a blacktop or
  concrete area of the playground.
• 1. For this activity, students work in pairs.
  (If there is an odd number of students, one group
  can have three members.) Provide each pair of
  students with a piece of chalk. This activity
  should be done at three different times
  throughout the day, preferably on the same day.
• 2. The first time, arrange students over the
  paved play area. Have them use chalk to sign
  their names on the pavement by the positions they
  take. Then have them mark an X next to their
  names, and stand on that X. Have each student
  mark the spot where her or his partner's shadow
  ends, and measure the length of the shadow from
  the X to the end of the shadow. Mark that length
  and the time of day by the end of the shadow.
  Also, have students note the approximate position
  of the sun in the sky.
• About two hours later, repeat the activity. Have
  students stand on the X in the exact same
  position stood in when they made the previous
  measurement. Mark the end point of the shadow and
  the time of day, just as in the first step.
  Measure and mark the length of the second shadow.
  For each student, determine the difference in the
  lengths of the two shadows. Also, have students
  note the approximate position of the sun in the
  sky. Has the sun's position changed since the
  first measurements were made?

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Developing The Lesson - 2

• 4. Have students complete a chart showing the
  times, shadow lengths, and the differences among
  shadow lengths. Then make time for students to
  share the results of the experiment with their
  classmates. Discuss why the shadow lengths
  changed from one time of day to another. Do any
  students connect the shadow measurements to the
  fact that the sun's position in the sky also
  seemed to change throughout the day? Help
  students understand that the position of the sun
  is the determining factor in the length of the
  shadow. The sun's position changes throughout the
  day. Since their positions (when measuring their
  shadows) did not change, the sun's position was
  responsible for the differing positions and
  lengths of their shadows.
• As a follow-up activity, have students predict,
  note, and measure the lengths and positions of
  the shadows of other objects on the school
  grounds -- for example, the school itself, the
  flagpole, a tree
• From http//www.education-world.com/a_lesson/04/l
  p330-05.shtml

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Closing The Lesson
Build Your Own Sundial Show students a picture
of a sundial. Ask them if they know what this is
and how it works. Describe and name the two
parts of a sundial Review the student
instructions for building a sundial. Explain to
students that their performance on this lesson
will be based on their ability to carefully
explain how a sundial works. From
oz.irtc.org/ftp/pub/stills/1996-06-30/sundial.jpg
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Sundial Templates
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Teacher Resources

• Tracing a Shadow
• Lamp with no shade Masking tape Chair
  Black marker or crayon
• Large sheet white paper Glue Magazines
  Scissors
• Follow Your Shadow
• Chalk Clear paved area
• Animal Shadows
• Copy of the Animal Shadows sheet
• Overhead or slide projector
• Build Your Own Sundial
• Scissors Compass Scotch tape Craft
  knife

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Enrichment Activities

• Have students complete the
• Animal Shadows activity.
• Here are two childrens books that could be used
  to supplement this lesson.

Shadow Blaise Cendrars
Shadows on the MoonJolyon Byerley
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Standardized Test Items
Source http//www.pen.k12.va.us/VDOE/Assessment/r
eleasedtests.html
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Shadows and LightFor the Student
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Tennessee Learning Goals

• Earth and Space Science
• Content Standard 7.0 Earth and Its Place in the
  Universe The student will investigate the
  structure of the universe.
• Third Grade Benchmarks
• Learning Expectations
• 7.2 Recognize that there are predictable patterns
  which occur in the universe.
• Performance Indicator Teacher
• at Level 3, the student is able to
• 3.7.tpi.7. design an exploration for comparing
  the length of a shadow at different hours of the
  day.
• Fifth Grade Benchmarks
• Learning Expectations
• 7.1 Know that objects in space have identifiable
  characteristics, such as appearance, location,
  and apparent motion.
• 7.2 Investigate the patterns and movement of
  objects in space.
• Performance Indicator State
• at Level 3, the student is able to
• 4.7.spi.3 recognize that the length and position
  of a shadow is related to the location of the
  sun.

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Student Assessment

• You will be assessed on your ability
• to explain how a sundial can be used
• to tell the time of day.
• In your explanation, you must properly
• use all of the following terms
• Shadow Gnomon Sun
• Compass Light Compass

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Tracing a Shadow

• What causes shadows?
• What causes day and night?
• You will need
• Lamp with no shade Masking tape
• Chair Black marker or crayon
• Large sheet white paper Glue
• Magazines Scissors
• Place a chair close to a wall with nothing
  hanging on it. Turn the chair sideways. Leave
  enough space for you to walk between the wall and
  the chair.
• 2. Have your partner sit in the chair. The lamp
  should be placed at the spot where you stopped.
  It needs to be on top of something that is as
  high as her head. The room should be dark except
  for the light from the lamp. Your partner's face
  and head should make a shadow on the wall.
• Tape the large sheet of paper to the wall where
  you see the shadow. Trace the outline of her face
  onto the paper. Cut out the face and fill it with
  a collage of magazine pictures that show things
  you like.

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Follow Your Shadow

• In this lesson, you will investigate shadows and
  study how the position of the sun and time of day
  affects a shadow.
• 1. For this activity, you will work in pairs.
  All you need is a piece of chalk.
• 2. Sign your names on the pavement by the
  location you are using.
• - Mark an X next to your names, and stand on
  that X.
• - Mark the spot where your partner's shadow
  ends, and measure the length of the shadow from
  the X to the end of the shadow.
• - Mark that length and the time of day by the
  end of the shadow.
• - Make a note of the approximate position of
  the sun in the sky.
• 3. About two hours later, repeat the activity.
  Be sure to stand on the X in the exact same
  position stood in when you made the previous
  measurement. Mark the end point of the shadow and
  the time of day, as in the first step. Measure
  and mark the length of the second shadow.
• - Determine the difference in the lengths of
  the two shadows.
• - Note the approximate position of the sun in
  the sky. Has the sun's position changed since the
  first measurements were made?
• 4. Complete a chart showing the times, shadow
  lengths, and the differences among shadow
  lengths.
• Discovery Questions
• - Why the shadow lengths change from one time
  of day to another?
• - What caused the change in the length of your
  shadow?
• - Is there a connection between the shadow
  measurements and the sun's position in the sky?
• - How does the position of the sun affect
  length of the shadow?
• - What other objects in your school yard cast
  shadows? Will their shadows be affected like
  yours was?

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Build Your Own Sundial

• Print the sundial base and the gnomon.
• You will need Scissors Compass Scotch tape
  Craft knife
• Place the main sheet on a hard surface and using
  the craft knife, cut down the line that says 'cut
  here' (ask an adult to help you).
• Using the scissors, carefully cut out the
  template for the gnomon, the triangle shape. Once
  you have done that, fold it along the line.
• Now place the gnomon inside the slit of the
  sundial template. You must make sure the
  right-angle is at the bottom of the sundial
  template.

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Build Your Own Sundial

• 6. Now using the tape, stick the bottom of the
  gnonom to the base of the sundial. The gnomon
  should stand up by itself, but you may need to
  secure it with some more tape at its base.
• 7. Find north with the compass - you'll need to
  slowly turn in a circle until the pointer points
  north.
• 8. Once you find north, place the sundial on a
  flat surface and line up the arrow on the top of
  the sundial so it points north. Make sure the sun
  is shining!

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Enrichment Animal Shadows

• You can explore the concepts of lenses,
  magnification, and reflection.
• Material
• 1 Copy of the Animal Shadows sheet
• 1 Overhead or slide projector
• Safety
• Be careful around the projectors. Do not look
  directly into the light!
• Preparation
• Set the projector up so that it projects onto a
  white wall with nothing on it.
• Procedure
• Using the sheet, take turns making animal
  shadows. Make sure everyone gets a chance.
• What other fun shapes can you make?
• Questions
• When there is no light, we see black. What
  causes these shadows?
• Does a shadow really exist, or is it something
  our mind produces?