Ask: What is a Light Source?
Objects or materials that give off or emit light
I. Light Source Sorting Activity:
Demonstrate and model the steps
Explain what a light source is (objects that give off light).
Show the objects one by one and describe as a light source, or not a light source and explain that it either gives off light or does not give off light.
Place two labeled paper plates on each desk (Light Source, Not Light Source)
Approach each student with two objects: one light source object, and one object that is not a light source.
Given two choices, students identify the object that is a “Light Source” and place it on the paper plate. Guide the student’s choice by asking “Which object gives off light?”
Direct the student to place the other object on the plate labeled “Not Light Source” and explain that the other object does NOT give off light.
If time, allow each student to take two turns, or finish sorting the objects as a demonstration.
Divide the Science Lab Work Surface in half with masking tape and label one side “Light Source” and the other side “Not Light Source.”
Ask each student to place their objects on the correct side of the table.
Summarize or confirm the final conclusion by naming the light sources collected and sorted, then name the objects that are not light sources.
II. Properties of Light
Light travels in a straight line.
a. Punch holes in several index cards.
b. Line the cards up using holders and a straw so that the light hits a block.
c. Remove the straw and shine a flashlight through the holes and onto the block.
d. Notice how the light goes through the holes.
e. Slightly move one of the cards to the right or left.
f. Shine the light through again, and notice that the light is blocked
g. Attempt to line up the holes without using the straw so that the light hits the block.
Reflection: light bounces off of some materials or objects
a. Place a large white sheet of paper on the desk or work surface.
b. Stand the black cardboard with the slit aligned with the long edge of the paper.
c. Shine the light through the slit and observe the ray of light on the paper.
d. Trace the light with a pencil.
e. Place a mirror in holders, on the long edge opposite the black cardboard.
f. Shine a flashlight through the slit in the black cardboard and into the mirror.
g. Observe the reflection of the light coming out of the mirror.
h. Move the black cardboard to a corner of the paper across from the mirror.
i. Shine the light through the slit and into the mirror.
j. Observe the reflected light on the paper.
Absorption: light is taken in by some materials or objects
a. Replace the mirror with black paper and repeat the above steps
b. Notice the light does not come back because it is absorbed, taken in.
Refraction: light can bend when it goes through some materials
a. take away the paper or mirror and place a prism or glass of water in the
center of the paper.
b. Shine the light through the slit in the black cardboard
c. Notice the light will bend and come out at a different angle.
III. Additional activities or examples of observations involving light energy
Observe your image in a variety of mirrors and reflective surfaces: concave mirror, convex mirror and a double mirror (spoons work well)
Shine the light into the large mirror and find its reflection in the room.
Place a pencil in a cup and observe that it appears bent.
Place a penny under a cup and add water, and the penny appears to disappear.
Shine a light through a prism and observe rainbows.
*Note: If permitted, laser lights work best for these activities.
Shine a light on a variety of materials (plastic bag, waxed paper, colored plastic, colored paper, black paper, white cloth, black cloth, foil, wood). Ask students “How much of the light goes through (all, some, none). Can you see a clear image (all), fuzzy image (some), no image (none). The light that does not go through is reflected and absorbed.
Take the temperature of materials (water, sand) before and after exposed to light.
Place ice cubes under a light, one on white material and one on black material, and observe which one melts first.