To investigate shadows, using literature-based discussion as well as experiences with manipulating shadows.
This lesson is part of a four-lesson series in which students observe the daytime and nighttime sky regularly to identify sequences of changes and to look for patterns in these changes. At the K-2 level, learning about objects in the sky should be entirely observational and qualitative. The priority is to get students noticing and describing what objects in the sky look like at different times. (Benchmarks for Science Literacy, p. 62.)
The sun, moon, stars, clouds, birds, and airplanes all have properties, locations, and movements that can be observed and described. Ideally, students should engage in direct observation of both the daytime and nighttime sky throughout this lesson series. However, the recommended Internet resources can be helpful to enhance student experiences, or if opportunities for direct observation are limited. This investigation requires that observations be ongoing, so that students can look for patterns over time. As children become more familiar with objects in the sky, they can be guided to observe changes, such as night and day and the seasons.
In Sky 1: Objects in the Sky, students investigated objects in the daytime and nighttime sky.
In Sky 2: Shadows, students explore making shadows and tracking the movement of an object over the course of a day to look for patterns. It is best to couple this shadow activity with reading the book, Bear Shadow, and making a map of Bear's neighborhood when the sun is relatively high in the sky, either near the beginning or the end of the school year. You'll want to measure sun shadows at least twice and perhaps three or four times during the year to see how they vary with the time of year.
In Sky 3: Modeling Shadows, students construct models to demonstrate their understanding of shadows.
Sky 4: The Moon has students drawing the moon's shape for each evening on a calendar and then determining the pattern in the shapes over several weeks.
Ideas in this lesson are also related to concepts found in these Common Core State Standards:
- CCSS.ELA-Literacy.RI.2.1 Ask and answer such questions as who, what, where, when, why, andhow to demonstrate understanding of key details in a text.
- CCSS.ELA-Literacy.RI.2.6 Identify the main purpose of a text, including what the author wants to answer, explain, or describe.
- CCSS.ELA-Literacy.RI.2.7 Explain how specific images (e.g., a diagram showing how a machine works) contribute to and clarify a text.
- CCSS.ELA-Literacy.RI.2.8 Describe how reasons support specific points the author makes in a text.
This lesson uses the book Bear Shadow by Frank Asch.
Either individually or as a participatory exercise, you and the students should read Bear Shadow by Frank Asch and discuss. In this story, a bear attempts to escape a shadow that seems to be chasing him. If this will be the introduction to a study of shadows, with particular emphasis on those caused by the sun, spend time finding out what students already know about shadows. You might guide this discussion by asking questions such as:
- 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?
Use the responses to help the children shape activities through which they will discover the answers to their questions.
If you have already begun the study of shadows and have measured sun shadows at least once, your discussion of Bear Shadow can be more pointed. In addition to the kinds of questions above, you can, for example, discuss the time of day when the various events occur and the direction Bear's shadow will fall at these times.
Eye on the Sky offers various astronomy topics and activities. For this part of the lesson, read What Makes Shadows? Observing and Drawing Shadows, and complete the suggested activities with students. Here, students create and trace shadows of each other. This activity includes a thorough list of discussion questions, as well as ideas for extending a study of shadows. In addition to the questions included in the lesson, ask students:
- How can you "make" a shadow?
- What is the light source?
- How is the shadow similar to the object you used to make it? How is it different?
- How can you change the size of your shadow?
- How can you change the shape of your shadow?
- How can you change the position of your shadow?
Now your students will build sundials and track changes in shadows over the course of one or more days. To do this activity, you can use the Sundials: Observing and Using Shadows activity from the Eye on the Sky site.
For the first part of this activity, your students should build their own sundials using the paper plates and straws. In addition to the directions on the Eye on the Sky site, you may want to ask your students to mark compass positions of North, East, South and West on the paper plates. This will help them to reposition their plates each time they go outside. This activity may take about 30 minutes for students to complete.
When you're ready for students to move outside, find some open outdoor space—preferably in the school yard—that can be used every day. Be sure to choose a spot unobstructed by trees or tall buildings which would shade this area early or late in the day. After selecting a suitable spot, use a compass to determine North, East, South, and West.
Students should visit their sundials throughout the day, taking periodic measurements by tracing the line of the shadow and marking the time of day. They can record their measurements on the Sundial Data Sheet. Encourage students to begin making predictions about where the shadow might fall next.
Each time students visit the sundial in the course of the day, ask them to compare the new shadow line to those drawn previously: Has it changed? How has it changed?
At the end of the day, students should bring the sundials inside. Ask students to look at the information they recorded on their data sheets. Use that information to create a bar graph that represents the length of the shadows at the various times observed.
- What does the graph look like?
- When is the shadow shortest?
- When is it longest?
- What do you notice about the lines? Does the pattern of the lines remind you of anything?
Reread Bear Shadow. As a class, identify those aspects of the story that are purely fictional and those that “could happen,” paying particular attention to how shadows change during the day. Compare the shadows in Bear Shadow to those students made and tracked in the Development activities. You could revisit the discussion questions listed in the Motivation, especially focusing on the last one, "What other questions do you have about shadows?" You could spend time answering the students' questions, as well as generating ones to be answered in the other lessons of this series.
As a class, create a nonfiction version of the story in Frank Asch's Bear Shadow.