Is It Clear?


…an absorbing and reflective investigation into the properties of materials

Flashlight

  • Light is required to see.
  • Light and sound are forms of energy with specific properties.

Inquiry Skills Used

This is a research activity using various primary and secondary reference sources.

Safety Considerations

Remind students of expectations when in a darkened room.  Students should not be directly shining the light into any eyes.

Background

Materials often behave differently when placed in a beam of light.  This experiment helps children understand these differences and become familiar with the properties of opacity, translucency, and transparency.

Washing window

What You Need

  • Flashlight
  • Black paper
  • White paper
  • Aluminum foil
  • Wax paper
  • Clear plastic wrap
  • Groups of four people

Looking in mirror

What to Do

  1. Make the classroom as dark as possible.
  2. Have one student hold the flashlight and shine it downwards onto the piece of paper held by the second student.
  3. A second student sits in a chair and holds the piece of paper/wrap in front of them, angled toward their face (as if they were ‘reading’ the paper).
  4. The third student looks at the face of the student holding the paper, judges and assigns a score to the amount of light they see shining on the second student’s face.
  5. The fourth student looks at the floor below the paper, judges and scores the amount of light they see.  (Example for scoring 1–no light, 2–a little light, 3–lots of light, 4–as much light as the flashlight gives off.)

For the black paper, the judges will see little or no light shining on the second student’s face or on the floor.  The black paper absorbs virtually all of the light.

For the white paper, the second student’s face has a lot of light shining on it as most of the light is reflected, some is absorbed, but little goes through the paper to the floor below.

With aluminum foil, all the light is reflected into the student’s face, ‘none’ is absorbed, and none passes through and shows on the floor below.

With the wax paper, some light shines on the first student’s face, and some shines on the floor below the paper.

With the clear plastic wrap, little if any light shines on the student’s face who is holding the wrap and the floor is lit up under the wrap as virtually all of the light shines through the clear plastic onto the floor below.

Tape

 

 

Properties of Light

  • absorbs or reflects all light–opaque
  • absorbs or reflects some light, some still passes through–translucent
  • absorbs or reflects ‘no’ light (and if it did, you would not be able to see it–like walking into extremely clean windows)–transparent

Where to Go from Here?

Students can identify examples of opaque, translucent, and transparent materials found around their homes that are both manufactured as well as naturally occurring.

A parallel investigation could be conducted into materials that absorb or reflect sound.

STSE Links

How can we use this information to create a window that allows people to see out but people on the outside cannot see in?

Cross Curricular Connections

Language

  • Write a lab report including questions, predictions, materials and procedures, observations, and conclusions for an experiment to investigate the basic properties of light or sound. (ST 2.2, 2.3)

Credit Where Credit is Due

Adapted from Discovering Science–Heat, Light and Sound, a Frank Schaffer Publication.

Grade 4: Matter and Energy

Contributed by: Ellen Webb

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