This is the first Investigation in the LabLearner CELL Light and Optics. Students will observe that the amount of light that is transmitted or absorbed depends upon the shade of the object.

Students will also investigate how transparent objects are able to reflect, transmit and absorb light, while opaque objects absorb or reflect but cannot transmit light.

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A. Begin the Investigation by explaining to students that this CELL will explore light. Prompt students’ prior knowledge by asking students to use the Recall Tool.

Ask students: What do we do when getting ready to learn something new? Students should realize that the Recall tool is appropriate.

Pose the following questions to prompt student recall about light:

1. What is light? Student answers will vary. Light is a form of energy that is visible to the human eye and allows us to see things around us.

2. Why do we need light? Student answers will vary. Examples may include: we need light to see where we are walking, we need light to see to do our homework, plants need light to grow, and we need sunlight to make Vitamin D.

3. Why is it more difficult to see during the night than it is during the day? There is little or no light at night that allows us to see things around us. Sunlight during the day allows us to see objects around us.

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B. Ask students to refer to the terms absorb, transmit, and reflect from their Scientist’s Glossary. Inform students that these terms describe different ways in which light is able to interact with different substances.

1. Ask student volunteers to read the definition of each term aloud to the class:

“Absorb: To take something in and make it part of the whole.”

“Transmit: To transfer from one place or substance to another.”

“Reflect: To bounce back or bounce off.”

2. Ask students: Have you heard of the terms absorb, transmit and reflect? Student answers will vary.

3. Ask students as a class to create sentences utilizing these terms in the correct context. Sample sentences are provided below.

• The lotion that I just put on my hands has been absorbed by my skin.
• The signals from my favorite radio station are transmitted through the air to my radio.
• When I look in the mirror, I often smile at my reflection.

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C. Inform students that the terms absorb, transmit and reflect are often used when describing the behavior of light. Inform students that three volunteers are needed to illustrate the meaning of these terms as they relate to light.

1. Inform the first student volunteer that they will represent light. Indicate the square of tape on the floor and inform the class that the square represents an object that is able to absorb light.

a. Instruct the student representing light to walk toward the square. After the student enters the square, instruct them to remain inside and not to exit.

b. Inform the class that the light entered the square and because the light did not pass through it, the light was absorbed by the square.

c. Inform the class that in this example, the square is made of a substance that allows it to absorb light.

d. Ask the student to exit the square and return to his or her seat.

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2. Inform students that the square will now represent an object through which light is transmitted.

a. Ask the student representing light to walk toward the square. As the student enters the square, instruct them to continue walking through the square and out the other side.

b. Inform students that light entered the object and because the object transmits light, it was allowed to pass through and exit the object.

c. Inform the class that in this example, the square is made of a substance that allows it to transmit light.

d. Ask the student to return to his or her seat.

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3. Inform students that the square will now represent an object that reflects light.

a. Instruct the student volunteer to walk toward the square on the floor. Direct the student to approximate “bouncing” off the edge of the square. Instruct the student not to enter the square but approach the edge, step on it with one foot, and then walk away from the square in a different direction.

b. Inform students that light approached and hit the surface of the object but because the object reflects light, the light did not enter the object or pass through it, it bounced off.

c. Inform the class that in this example, the square is made of a substance that allows it to reflect the light.

d. Ask the student to return to his or her seat.

Note to Teacher: When light is transmitted by an object or reflects off an object, it travels in a path that is determined by both the interaction of the object with the light and the original direction of the light. This role-play is designed to aid students in understanding the concepts of absorbance, transmittance, and reflection, not to illustrate the specific direction of light. The path of light during transmittance and reflection will be further explored is subsequent Investigations.

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D. Inform students that the behavior of light depends on many different factors. One factor is the shade of color of an object.

1. Ask a student volunteer to read the definition of shade from the Scientist’s Glossary.

“Shade: The degree of darkness of a color.”

2. Show students the piece of black paper and the piece of white paper. Ask students Which color is a darker shade? Black is a darker shade than white.

3. Explain to students that a color that is close in shade to black is another dark color. The closer a color is to black, the darker it is. A color close in shade to white is another light color. The closer a color is to white, the lighter it is.

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E. Inform the class that you will illustrate the differences in shade by making a continuum representing different shades of the color blue.

1. Instruct students to work in pairs and place each of the shades of blue in order from darkest shade to lightest shade from left to right. The darkest shade of blue should be placed on the far left on the continuum, and the lightest shade should be placed on the far right.

2. After students have had sufficient time, ask them to share their conclusions with the class.

The correct order from left to right:  D    C    E    B    A

F. Finally, inform students that they will answer the following question about absorption and reflection in the Lab:

Do different shades of colors absorb or reflect light differently?

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This final slide is just plain fun and immensely interesting, although outside our immediate lesson. It shows an optical illusion. Believe it or not, the two squares marked A and B are of the exact same shade. This illusion demonstrates that our eyes, and more importantly, our brains interpret much of what we see in terms of the things around them. 

The video below simply adds a grey rectangle the same shade as squares A and B, connecting the two boxes. This is a really good optical illusion because even when you know the true situation, your brain will tend to revert back to your initial impression.