Science in Focus: Shedding Light: Lights, Camera, Action
IV. Do It With Your Students
Create your own set of photographs for your students. Compose and take five photographs on a sunny day so that a person with knowledge gained from "Sun and Seasons" could arrange them in the order in which they were taken. You might use the photos from your Buddy Activity as well.
Each picture should be composed so that a clearly visible shadow and the object casting the shadow form the central subject. A suggested group of photographs would be one picture each at about 8:00 am, 10:00 am, 12:00 pm, 2:00 pm, and 4:00 pm, in order to provide a wide range of shadow angles. For each photograph, record the compass direction (heading) in which the picture was taken. The photographs are presented to the student along with the compass heading. The student must infer the time of day from the shadow for each picture and arrange the pictures in chronological order.
Dimensions to consider in composing a group of pictures include:
- Direction or heading: Are all the pictures taken with the same or different headings? Varying the direction of the camera adds additional spatial challenges.
- Objects photographed: Is the same object used in all photos or are different objects used as subjects to cast the shadow? Using different objects adds complexity to the problem.
- Height and shape of object: Are all objects about the same height and shape or do they vary?
- The shape and size of the shadow in the picture can add different types of challenges. Long, thin shadows are more easily interpreted than wide, fat shadows.
- Time of year: Are all the photos taken in the same day or spread out significantly across the year? Shadows are longer during the winter than during the summer at any comparable time of day.
A simpler version of this activity is to have students take a picture inside or outside the school and challenge other students to stand where the photographer stood to take the picture. This would promote visual thinking skills important to the study of seasons. This activity could be done more interactively with a digital camera or use of video tape where the scene is captured with "still" mode on the tape. An extension of the activity would be to video tape a shadow stick while placing a light in different locations. When replaying the tape, students would be challenged to identify the location of the light. Based on the length of the shadow, they could determine the height of the light.
You might also try the Buddy version of this activity with a pen pal classroom if you have one.
In composing pictures consider the following factors:
- Bright sunlight is critical.
- High contrast background for the shadow is best - shadows across a grey street surface will not show up as well as shadows across white cement sidewalks or green grass. Many surfaces, however, are quite usable for most students.
- High contrast between the object and its background: A road sign will show up better against a light, uniform background than a dark building.
- Absence of other shadows is best, especially those shadows that are straight and could be confused as the subject of the photograph.
- Classroom sets of photographs can be made inexpensively by photocopying. This duplication process will work only with high contrast photographs. If this is the process to be used, take the original pictures with black and white film.
- The photos can also be duplicated by scanning them into a computer file and printing them on a color or black and white printer.
Variation for the Younger Learner
Generate experiences in the classroom where younger students observe long and short shadows outdoors. Follow this by creating long and short shadows in the classroom with artificial light. Discuss the location of the light source relative to the object casting the shadow. As a step toward interpreting pictures, have students observe the creation of classroom shadows by using a video camera. Students observe the TV monitor and discuss the location of the light source. Using pre-recorded images, ask students where the camera was located to take the pictures (e.g. by the door, near the teacher's desk, by the sink, etc.).
Looking for more? Check out references and information in V. Resources.