Science in Focus: Shedding Light: Lights, Camera, Action
III. Do It Yourself
How does the time of day, the position of the Earth, or your location affect the shadows that you see? In this activity, you'll work with a Light Buddy to explore these ideas. Conduct an activity similar to the ones you saw in Workshop 7. You and your Buddy will be setting up a Shadow Stick and tracking shadows throughout the day. You can share your notes over the Internet or via postal mail.
The Annenberg Channel in Cambridge, MA, worked with our Light Buddy in Los Angeles, CA on this activity. After you've completed the activity, take a look at our results here.
Before you begin: You will be comparing shadows with your Light Buddy. Read through the activity before conducting it. Think about what sorts of results you and your Light Buddy might get. In which direction will your shadows point? What will they look like? Write down your predictions.
- One 12 inch ruler lightweight (opaque plastic is best)
- One letter sized manila folder
- molding clay, Play-Doh ®, or other moldable material to secure the ruler to the base
- pencil and paper
Scouting the location:
- Locate a flat surface outside that receives sunlight at the times you will be recording data. You may need to select multiple areas - one for each time of the day. Find your location before the actual data recording time.
The folder and ruler set up:
- Before the day of your experiment, you should set up your shadow stick on the folder (see below).
- Open the manila folder.
- Draw a line along the center crease of the folder.
- Then draw another line perpendicular to the line drawn in step 2.
The line should be one inch from the edge of the open folder. You will
eventually position the ruler vertically on the crosshairs of this intersection.
The flat edge should follow the line along the crease of the folder.
- Position the ruler. Using the molding clay or other material, create a base for the ruler to stand in. Clay should be pressed into the folder. Insert the ruler into the mound. Ensure that the ruler is perpendicular to the folder and centered on the crosshairs of the line. Make sure that the ruler is secure and stable.
- On the opposite line along the crease, draw an arrow and write the letter "N" for north.
Selecting a day that works for you and your Buddy
You and your buddy should find a day when you are both available at the same time. You might try two or three times throughout the day, keeping in mind the time difference, when the Sun sets in each of your locations, and your resepctive schedules.
You might try times such as:
- Buddy 1 (PT): 9am 12pm 3pm
- Buddy 2 (ET): 12pm 3pm 6pm
You may also want to check the weather to ensure you will both have a sunny day.
Some useful weather Web sites :
- The Weather Channel http://www.weather.com
- Interactive Weather Information Network (IWIN) http://iwin.nws.noaa.gov/
- USA Today Weather http://www.usatoday.com/weather/wfront.htm
- CNN Weather http://www.cnn.com/WEATHER/
Positioning your folder on the record day
In your sunny spot, set your folder on a flat surface. Using your compass, position the arrow and the "N" on your folder directly north.
Taking the photos and recording the data
- In order to control the distance from the ground from which the photos are taken, try to fill the folder completely in the frame of the camera's viewfinder. Take at least one photo in this manner. If the shadow falls outside of the folder, then take other photos from different angles to capture the shadows.
- If you have time, you might measure the shadows or indicate a scale in your photo with another ruler.
- Be sure to keep your shadow out of the photo.
- Be sure to record the numbers of the photo and the times that they were taken.
- Repeat this set up and process at each of your designated times.
Sharing your photos
- If you have a digital camera, you might try emailing your photos to your buddy, or setting up a Web site.
- If you have a traditional camera, make double prints of your photos and send one set to your buddy. Be sure to label the photos with times on the back of the photograph.
Compare and contrast the photos
- How do your results compare to your predictions?
- What did you find surprising or new?
- Share your results with your Ligh Buddy. How does your location affect your results?