Global Shadow Tracking

Process

A family and their shadows go for a walk.
This science investigation was designed to unfold over the course of one school year.  Students conduct the shadow investigation one morning a month over the course of the year -- or as many monthly observations as possible given variations in school calendars worldwide.  Teachers looking to use this activity as part of their class curriculum should follow the steps outlined below.

This lesson is based on the Pooled Data Analysis, Information Collection, and Database Creation Activity Structures, and the Collect, Share, and Compare, and the Collaborate/Co-construct Action Sequences as described by Judi Harris.

Overview
In "Shadow Tracking," students explore what makes shadows and how shadows move throughout the day. Working in collaborative groups, students go outside and trace a person's shadow on the playground. They do this in the morning and, for the first investigation only, again in the afternoon. They record the position of the Sun in the sky, and measure the length of the shadow, and they predict  where they will find the shadow when they observe it again in the afternoon. They relate the change in their shadows' position to the change in the Sun's position in the sky.

In "Global Shadow Tracking," students share the data from each monthly investigation with other students around the world. The telecollaboration happens when students share data from partner schools at different latitudes, including some in the opposite (northern or southern) hemisphere.

Lesson Plans


Pre-lesson Preparation
  • Introduce/review how to work in collaborative groups.
  • Introduce the compass. Demonstrate for students how to use a compass and teach them the four cardinal directions (north, east, south, west). Also, demonstrate the intermediate directions (northeast, southeast, northwest, southwest). Practice as a class and then in collaborative groups, identifying the cardinal direction of objects in the classroom or on the school campus. You may also want to label the cardinal directions in the classroom and with chalk on the playground.
  • Divide class into groups of three or four for "Shadow Tracking."
  • Decide how students will record their observations and data. A science notebook or a worksheet is suggested. (FOSSWeb provides information about using science notebooks.) One idea is to give the students a blackline master of a compass on which to draw the shadow and record the time of day. Note, the student's feet (or bottom of the shadow) rest on the center of the compass. This will allow the students to identify the direction of the shadow accurately.
  • Identify a flat concrete area, away from buildings, that can be used for this investigation.
  • Gather materials for each group: compass, tape measure or ruler, chalk, science notebooks or worksheet, pencils.
  • Check the weather forecast since this investigation needs to be completed on a sunny day.

Step 1: Thinking about the Sun
  • This investigation should be done during the first week of the month.
  • Discuss daytime sky observations with a focus on the Sun.
  • Ask general questions but also ask questions that get the students thinking about the apparent movement of the Sun.
  • Get students thinking about where  the Sun rises and sets.
  • Optional: Record on chart paper.

Step 2:
Shadow Tracking, Morning Observation
  • Review cardinal directions with students.
  • Ask students, "What is a shadow and how is a shadow made?" and "How do you make a shadow indoors? Outdoors?"
  • Practice making shadows outdoors.
  • Tell students they will be working in collaborative groups and take turns drawing around the outline of their partners shadows. Remind students that they will need to be far enough apart so that the shadows don't overlap.
  • Around 10:00 a.m., go outside to start the investigation.
  • One by one, each group member stands with his/her back facing the Sun, while the other group members traces the outline of his/her shadow with chalk. (Don't forget to trace around the student's feet/shoes also--this will make it easier to do the second and third observations.)
  • Label the inside of the shadow with the student's name and the time of day.
  • Next, record in centimeters  the length of the shadow from the heals to the tip of the student's head.
  • Also, record the cardinal direction the shadow is pointing in.
  • Record the position of the Sun in the sky.
  • Repeat until all group members' shadows are traced.
  • Finally, make predictions about where/how the shadows will change and/or move. You could ask, "At noon will your shadow at noon be exactly in the same spot?"

Step 3: Shadow Tracking, Mid-day Observation
  • At mid-day go outside to do the second observation.
  • Repeat the shadow tracing again. Be sure to label the new shadows, record the length, the  cardinal direction of the shadow, as well as the Sun's position in the sky.
  • Predict about where/how the shadows will change and/or move in the next two hours. Record predictions.
  • If clouds obscure the Sun for the second (or third) observation, it is recommended you repeat the investigation from this step on the following day.

Step 4:
Shadow Tracking, Afternoon Observation
  • At about 2:00 pm go outside to the third and final observation.
  • Repeat the shadow tracing again. Be sure to label the new shadows, record the length, the  cardinal direction of the shadow, as well as the Sun's position in the sky.

Step 5: Summarize
  • Look at all three shadows and discuss the changes. Focus the discussion on what they observed, why they think the shadow changed, and how the time of day affects the length of a shadow?
  • Have students discuss these changes in their groups and then record their thoughts.
  • Share out whole class.
  • Assess student performance using the Science Curriculum Checklist for Students and the Cooperative Group and Self Assessment Rubric. (These can be located on our Resources page.)

Step 6: Compare and Contrast Data
  • Enter the data from your first investigation in your shared Google Form.  (There is a tutorial for creating your own Google Form on the Resources page.)
  • Upload photos from your local investigation.  It is recommended that all participating teachers set up Flickr (or other photo sharing) accounts where all photos for your group's project can be "tagged" with the same identifier(s) for easy searching.
  • Use the data from other your partners around the world, along with your own data to discuss the differences in shadows in other parts of the world. 
  • Focus the discussion on: what they observed locally; what they observe in other geographic locations; are there differences and/or similarities and if so, why?
  • Assess student performance using the Science Curriculum Checklist for Students and the Cooperative Group and Self Assessment Rubric. (These can be located on our Resources page.)

Step 7: Monthly
Shadow Investigations
  • Plan to make additional shadow observations each month.
  • Make observations at 10:00 a.m. (plus or minus 30 minutes) once a month, during the first week.
  • Remember to have students stand with their backs to the Sun when doing tracing the shadow outlines.
  • Be sure to upload your data to the Google form and any images from your investigations each month.
  • Continue to compare and contrast your data with data from other locations.

Step 8:
Culminating Activity
  • Plan a culminating activity for students to showcase their science work.
  • Some ideas include: website, podcast, PowerPoint presentation, or science fair.

Last updated on July 2, 2009. Based on a template from EDTEC 570 at SDSU
© Christina Lahr, Diane Main, and Karen McKelvey