Bright ideas for teaching about shadows - includes related articles on shadow making

Late one recent afternoon, as the sun began to shine into my third-grade classroom, a message mysteriously appeared on our floor: LION PRIDE INSIDE.

"Hey, those are the words on our window, too," one student noticed. "How did they get on the floor?"

Another kid suggested that it was the shadow of our message on the window, but wondered where it had been earlier in the day. This discovery was the beginning of our exploration of shadows. How to Make a Shadow, the activity on the next page, was one of our most fun and successful investigations.

There's no better time to carry out a study of shadows than around Groundhog Day. Every year, on February 2, thousands of people - including some of your students, I'm sure - await word from Punxsutawney, Pennsylvania: Will Phil the Groundhog see his famous shadow? Take your students outside and ask them: What determines whether Phil sees his shadow? If you've done the activity on the next page, you can expect answers such as, "On a sunny day, Phil blocks the rays of light and creates a shadow. On a cloudy day, though, he doesn't make a shadow because there are no direct rays for Phil to block."

WHAT MAKES A SHADOW?

Generally speaking, two ingredients are necessary for making a shadow - a light source and an opaque or translucent object. Because rays of light cannot pass through an opaque object, a dark shape of that object, or complete shadow, is projected. Translucent objects allow some light through, resulting in lighter or fragmented shadows. For the activity on the opposite page you'll need to collect a variety of objects: transparent objects (such as clear sandwich bags, blank overhead acetates), translucent objects (such as waxed paper, plastic cups), and opaque objects (such as blocks of wood, craft sticks, the kids themselves).

HOW MAKE A SHADOW

PURPOSE

To help students draw conclusions about shadows by experimenting with different materials.

PROCESS SKILLS

observing, predicting, comparing, classifying, communicating, collecting and recording information, making conclusions

MATERIALS

flashlights or direct sunlight, chart paper, a collection of objects (see page 90), copies of the Shadow Data Sheet (see example, above)

TIME NEEDED

30 minutes

1 Ask students to describe shadows they have seen. Guide them to the idea that a source of light is an essential ingredient for making a shadow.

2 Divide the class into groups of three and give each a Shadow Data Sheet (see example, right). In the OBJECT column, have students write down the transparent, translucent, and opaque objects they will be testing for shadows.

3 Ask students to anticipate which objects will make a shadow and record their predictions in the second column.

4 Give each group a flashlight and a sheet of chart paper to hang. One student should point the flashlight at the paper, the second student should hold the test object between the flashlight and the paper, and the third should record the group's observations in the OUR FINDING column on the data sheet. Suggest that students switch roles for each object they test. If it's a sunny day, consider doing the activity outside, using direct sunlight instead of flashlights.

5 After students have gathered their data, let them work together to draw conclusions about what it takes to make a shadow. Ask them to describe the kinds of objects that make shadows. How are they different from objects that don't make shadows? Students should recognize that the shadow-producing objects block light because they are solid or translucent. The objects that do not make shadows are clear.

PRIMARY EXTENSION

Ask students to go on a shadow hunt around school or home. In their science journals, have them draw shadows they find and describe the object that created each shadow, the source of light, and the surface on which they found the shadow.

INTERMEDIATE EXTENSION

Older students can explore how shadows created by the sun change size and direction. Have students, in pairs, go outside three different times on a sunny day. Each time, they should measure and record the length of one another's shadows, and note in which direction their shadows are pointing. The following day, let students compile data on a class chart. Ask them: When were shadows the shortest? The longest? Why would shadows change size? Have them think about how the position of the sun relates to the size and direction of their shadows.

YOUR Resources

Bear Shadow by Frank Asch (Prentice Hall, 1985). Kids learn more about shadows as Bear tries to escape from his.

Shadowgraphs Anyone Can Make (Running Press, 1991). How kids can use their hands to create fun shadow pictures.

Shapes and Things by Tana Hoban (Macmillan, 1970). Invites readers to guess the objects casting shadows.

LYNNE KEPLER teaches third grade at Clarion-Limestone Elementary School in Strattanville, Pennsylvania. She is the author of A Year of Hands-on Science (Scholastic Professional Books, 1996). To order a copy for $31.95, call (800) 724-6527.

COPYRIGHT 1997 Scholastic, Inc.
COPYRIGHT 2004 Gale Group