Investigating light a form of energy you can see gas house gang


Review with students what they know about light, where or what type of lights have they seen, and characteristics of light they have observed both indoors and outdoors. Also review sources of light (the sun, various types of electrical or other source-powered bulbs they know, etc.). Share with the students how we are going to investigate the properties of light and how it reacts to different materials around us.

– First explain to the students that light is a form of electromagnetic radiation, or energy that travels in waves. Give examples they would recognize such as the sun’s ultraviolet rays, an oven that uses micro waves to cook food, music that is heard because of radio waves, an x-ray machine used to make images of bones inside our body.

– Turn off the classroom lights and close blinds. Bring out a laser pen. Before turning it on, ask students what they think they will see on the whiteboard on the wall. Why do they think a red light dot will be seen and how will it travel to the whiteboard? Turn on the laser pen, point to the whiteboard on the wall, and observe the red dot. Were they correct? Then spray some of the fogger in the air to observe the straight line rays from the pen to the dot on the wall. Now they can see that light travels in straight lines.

– Next bring out a flashlight. Before turning it on, have students predict what they will see the flashlight do when it shines on the whiteboard. Turn on the flashlight and point to the whiteboard. Were they correct? Now ask the students to describe what they believe will happen if someone places a hand between the light and the wall. Ask a student to come up and do that. Discuss why the shapes on the wall are dark (the hand blocked the light).

– Turn off the light and tell students you will move one of the cards. Have them predict what will happen. Move one of the cards and turn on the flashlight. Discuss what they observe. Why can’t they see the light on the last card this time? Point out that the light was absorbed by the white card and not allowed to pass through.

– Each group will be given a flashlight. Have one person hold a sheet of paper about five inches above a table. The other person will shine a flashlight straight down onto the paper. Observe the light on the paper and see if the light is shining elsewhere. Write down observations in a student journal – if the light continued in a straight line and passed through the material or if it was absorbed by it.

– Continue experiment, one at a time, with other materials such as plastic wrap, wax paper, tin foil, and wood. Students should first predict and record what will happen to the light and write down each observation after the experiment. Discuss why the light acted differently each time and create a hypothesis.

– Have one student point the flashlight straight down, with the light off, while the partner holds a mirror about five inches from the table. Predict what will happen to the light and record. Turn on the flashlight and observe the light to see if it is shining elsewhere in the room. Write down that observation. Discuss why they see the light at another spot in the room – and write down that hypothesis.

– Use the flashlight and mirror to reflect the light so it is seen on objects easily found in the room such as a doorknob, clock, poster, etc. Have students draw a simple diagram of the classroom, where they are standing, and arrow directions on how the light travels from the flashlight to the mirror to each object.

Students need to be reminded that this is a hands-on scientific investigation and that appropriate behavior and handling of materials (especially flashlights) is expected. Safety is critical and the flashlight and mirror should never be aimed directly into anyone’s eyes.

To expand this lesson/experiment, students could keep a log for one week of all objects they find and observe how light interacts with it. This information could be recorded on a student-created organized list with the object name in the first column and the words absorb, pass through, or reflect in the second column. At the end of the week, ask students to share some of their findings with the group. Make a list on the board of the most common surfaces and light behaviors.

This activity is different from how the lesson was previously taught showing students how light travels in a straight line, through air and space, until it reacts with a material it hits. This was achieved by the use of the laser pen with the fogger spray, and with the index cards and flashlight.