Uploaded by Kristina Doles

Light Unit - 3rd 4th Grade

Day 1: Intro to Light and Eletromagnetic Spectrum
Light and the Electromagnetic Spectrum
Discuss what students know about light. Define in
Make sure to include explanation of light
waves going in all directions
○ Can be blocked, bent, or reflected
○ Rays travel at 186,000 miles per
second in straight lines from their
Discuss: Visible light makes up only a portion of
the electromagnetic spectrum. Discuss the
electromagnetic spectrum, add picture and
definition to journals.
Electromagnetic Spectrum:
Infrared Light
Insert info about infrared light here
UV Light
Info/Discussion: Do you know which of these light energy waves causes sunburn and can hurt our eyes.
(Answer: Ultraviolet light waves.) What do we do to protect ourselves from UV rays? (We wear hats, sunglasses
and sunscreen.)
How does light energy affect us? Our eyes are sensitive to the brilliance of sunshine. Ultraviolet light penetrates
clouds and fog, and is reflected back at us from snow and water. If unprotected from the ultraviolet waves, our
eyes can be burned and/or permanently damaged. We can reduce this risk by wearing a high-quality pair of
polarized sunglasses designed by engineers to limit the amount of ultraviolet light reaching our eyes.
Polarized Light
Info/Discussion: How do polarized sunglasses work? Well, if we have a piece of paper containing a vertical (up
and down) slit, what light do you think would pass through? Only waves in the vertical plane would pass through.
The same applies for a horizontal slit and horizontal waves. When light reflects off water, all of the waves are
oriented horizontally. This causes the intense glare off the water's surface you may have noticed. Polarized
sunglasses work much like a letter going in to a mail box slot. If the letter is not positioned correctly then it
cannot go into the mail box.
History Link: Years ago (even in prehistoric times), Inuit people (also called Eskimos) who live in the snowy Arctic
carved goggles of wood or bone with a narrow horizontal slit across the front. This allowed them to better see in
"white out" snow conditions when light was coming from every direction and all contours were missing. How do
you think this worked? How is this similar or dissimilar to the polarized sunglasses? (Answers: This is the same
way that polarized sunglasses work. The horizontal slits only allowed part of the light waves, the horizontal ones,
through to the Inuit's eyes.)
Add image on next page to journals and title “Polarized Light:
Light waves traveling in the same plane as the openings in a polarizing filter pass through it, while
all other waves of light are blocked.
Light waves traveling in the same plane as the openings in a polarizing filter pass through it, while
all other waves of light are blocked.
Light waves traveling in the same plane as the openings in a polarizing filter pass through it, while
all other waves of light are blocked.
Light waves traveling in the same plane as the openings in a polarizing filter pass through it, while
all other waves of light are blocked.
Experiment: Polarized Light: What do you predict would happen to light trying to pass through two polarized
lenses oriented perpendicular to each other?
two pairs of polarized sunglasses
piece of plastic polarized film (purchase at a hardware store)
Have one student put on a pair of polarized sunglasses and hold the plastic polarized film in front of
him/her. Then, slowly rotate the film in either direction.
2. What do you notice when the film is straight up and down? What do you notice when the film is rotated
90 degrees?
3. Have students record their observations and answer the questions on the worksheet.
What's happening? Light particles travel in waves. Every light wavelength in the visible spectrum corresponds to
a specific color (see Figure 1). White light contains all the visible wavelengths. A polarizing filter consists of many
parallel tiny openings. Light waves traveling in the same plane as the openings pass through the filter, while all
other waves of light are blocked (see Figure 5). Light that has passed through the filter is considered "polarized"
— its light waves travel in approximately parallel planes. The sunglasses' lenses and the plastic film are both
polarizing filters. When the plastic film is rotated to only allow light traveling in a horizontal plane to pass
through, fewer and fewer light waves can pass. When the two filters are oriented perpendicular to each other, no
light can pass. When the polarized lenses and the polarized film are oriented at 90 degrees, the lenses become
Day 2: Color
Have you ever noticed that the colors of a rainbow are always in
exactly the same order? What is that order? Add ROY G BIG
acronym to journal (optional: in color).
Observe prisms and add drawing to journal. This could be done
whole class as a directed draw or in small groups, depending on the
number of prisms available.
Info/Discussion: What's happening? Where do the colors come
Light travels through space in the form of waves. White light contains
all of the colors in the visible spectrum. Some light waves have long wavelengths, while others have short
wavelengths. Each wavelength produces a different color of light. Usually all the wavelengths of light blend
together to form white light. But when light enters a prism, it bends (refracts). Light waves of different
wavelengths bend by different amounts. The longest wavelengths bend the least. The shortest wavelengths
bend the most. This bending separates the light waves so each color can be seen. This band of colors—red,
orange, yellow, green, blue, indigo, and violet—is called a spectrum.
Raindrops behave like small prisms, so they bend the different colors of the sunlight and disperse them out into
a band of colors that appears as a rainbow.
Show students the Visible Light Spectrum visual aid (the same as Figure 1). Optional: Add sketch of
wavelengths to prism illustration.
Play with Spectrum Glasses
Day 3: Interacting With Light
1. Add definitions/illustrations in journal
a. opaque: No light passes through object (it’s either reflected or absorbed) construction paper
b. Translucent: Some light passes though object painters tape
c. transparent: Light passes through object packing tape
2. Add drawing in journal in sharpie. Cover with appropriate material and label.
3. Add definitions and sketches in journal
a. Light rays travel in straight paths through air, water, and space. When light encounters a material,
3 things can happen:
Reflection: it bounces back (direction changed)
Refraction: it slows down and bends
Absorption: it is taken in (as heat energy)
4. In small groups, students explore materials by holding them up to the window and recording answers
on Light Scavengers Worksheet
a. Each tray/group needs
magnifying glasses
glasses of water with a pencil in it
empty glasses
wax paper
clear plastic spoon
metal can
Popsicle sticks
5. Class Discussion/Teacher Demo Whole Group
● Transparent Glass - Hold up a flashlight to a clear piece of glass. Ask students if the glass
transmits (lets through) the light. (Answer: Yes) Tell them that the glass is transparent to light.
● Translucent Wax Paper - Next, hold up the flashlight to a piece of wax paper. Again, ask the
students if wax paper transmits light. (Answer: Some light goes through, but some does not.)
Explain that some of the light is transmitted through the paper, but some is absorbed and some of
it is reflected (bounces off). The wax paper is translucent to light. Can they think of anything else
that is translucent? (Possible answers: Some bathroom shower windows, clouds, certain types of
glassware, sheer curtains and fabrics, perhaps leaves.)
● Opaque Book - Now hold the flashlight up to a book. Does the book transmit light? (Answer: No)
What happens to the light? (Answer: It is absorbed, and a little is reflected.) The book is opaque
to light. Ask the students to think of other examples of opaque objects. (Possible answers: Walls,
trees, our bodies, furniture.)
● Reflective Mirror - Next hold the flashlight up to a mirror, but with the silvered side facing you, not
the students. Ask the students if this mirror is opaque. (Answer: Yes it is, none of the light goes
through the silver side of the mirror.) Is all the light absorbed? (Answer: No) Show them that light
reflects off the mirror to land on the wall. Mirrors and other surfaces reflect light.
● Refracting Prism/Magnifying glass/Bottle - Finally, hold up a prism (or a magnifying glass or a
bottle of water). Put an object behind it. Does the object look the same? (Answer: No) Why does it
look different? (Answer: The transparent material is bending the light that comes through it,
changing its shape.) The tendency of a light wave to bend as it passes from one transparent
medium to another is called refraction. Can also shine laser pointer through water to see light
6. Group Activity: Ask students to help you arrange the objects in a line from transparent to opaque
according to how easy it is to see through the object. Discuss the differences in transparencies of the
various objects.
Day 4: Lenses and Light
1. Write definitions in journals.
a. Lens - A lens is a piece of transparent material, usually glass, that has at least one curved surface.
The curved surface/surfaces of a lens bends the light (refraction).
Concave Lens - Thin in center, thick on edges, bends light rays inward.
Convex Lens- Thick in the center and thin at the edges, bends light rays outward
2. Model what happens to light when it hits a lens. Add illustration to definitions.
3. Experiment with a lens: Place the paper over the end of the flashlight. Play around with the distances
between the flashlight, magnifying glass, and “screen” and see if you can view the image. What do you
notice about the image? Teacher, watch linked video for more information and inspiration.
a. Materials
Square of paper (to go over flashlight)
Sharpie (to draw image or word)
Magnifying glass
“Screen” (Book with white paper taped to cover)
If time allows, quick activity: Have the students examine the pictures and words through the magnifying glass.
What happens if they hold the magnifying glass at different distances?
What's happening? Some students may notice that images flip when you hold the magnifying glass at a certain
distance. This is because the image converges at a focal point. When the image diverges beyond this point, its
orientation is flipped (see Figure 2).
Figure 2. An image seen through a magnifying glass held at a distance further away than the focal point appears
to be upside down.
Day 5: Human Eyes
Observe and record. Have students look at their eyes using a mirror. Draw and discuss what they see.
Pass out weak flashlights (covered with masking tape if needed). Have students experiment with shining
the light on their eyes, closing then opening their eyes, etc. Record observations.
2. Assemble layer diagram. Put together layered paper diagram, discussing parts as they are added.
Parts of the Eye and Their Functions:
Ciliary Body: muscles of the eye that squeeze and relax. When looking at something that is far away,
the muscles will relax and the lens will become smaller. When looking at something close, the muscles
will squeeze and the lens will become bigger.
Iris: the colored part of the eye. The iris controls the light that enters the eye.
Anterior Chamber: located between the iris and the cornea’s innermost surface. This area is filled with
Pupil: the black part of the eye. The pupil allows the light to enter the eye. When the light is bright, the
pupil is small. When the light is dim/ dull, the pupil is big.
Cornea: clear skin that covers the front of the eye. The cornea does not contain blood vessels.
Lens: works with the retina to ensure that the image the eye sees is clear.
Sclera: also known as the “white of the eye”. The sclera is a tough skin that covers the eyeball.
Retina: The retina is a layer of tissue located in the back of the inner eye that converts light images to
nerve signals and transmits them to the brain. There are receptor cells all around the retina, these are
the rod cells and the cone cells.
○ contains the rods and the cones. The rods help you see black and white and the cones help you
see colors. The rods and cones take the image you see and turn it into an electrical message.
This message is than transmitted to the brain for understanding.
○ Rods and cones are the parts that help see colors. Rods are used in a dark room, which is why
you often cannot see color very well. Cones are used in the light and are sensitive to three colors:
blue, green, and red.If someone is colorblind, one of the cones may be weak. For example, if
someone asks you, “What colors are on a stop light?” and you have a green deficiency, you will
see a yellow-green for the red part, a lighter shade of yellow-green for the yellow part, and gray
for the green part. Without the cones, we would not be able to depict what color an object is.
Show the students the “Colorblindness Test” pictures.
○ The rods are more numerous, some 120 million, and are more sensitive than the cones. However,
they are not sensitive to color. The 6 to 7 million cones provide the eye's color sensitivity.
○ The cones are less sensitive to light than the rods. The cones are responsible for all
high-resolution vision.
Macular: a sensitive area located in the center of the retina that helps to create centralized vision.
Vitreous: thick liquid of jelly consistency that covers the eyeball.
Optic Nerve: once the retina creates the message for the brain, it travels along the optic nerve.
Ora Serrata: located between the retina and ciliary body.
Rectus Medialis: keeps the pupil close to the midline of the body.
Eyelashes: help keep dust and dirt out of your eyes.
Eyebrow: help keep sweat, dust, and dirt out o your eyes.
Day 6: Peripheral/Forveal vision
1. Whole Group Activity: Viewing Image and Discussing Peripheral/Forveal Vision
a. Project picture of a railway at sunset.
Tell students to center their vision on the sun. Without changing their focus, they will
point out other details in the picture.
Hold a discussion or debate about why when we are gazing at something specific, we
can’t clearly see the objects around it.
2. Define in journals:
a. Peripheral Vision:
b. Foveal Vision:
3. Group Activity: Test Your Skills
a. throwing and grabbing an object (dice) right in front of the center of the vision. Then the object
will be thrown again, but to their sides. (Like in the National Geographic video.) Students will
discover that it’s much for challenging when using peripheral vision.
4. Discussion:
a. Is peripheral vision important? Why or why not?
b. Why can’t we clearly see the objects that surround a focal point?
5. Discussion/Information:
a. Display image of eye and review:
The retina is a layer of tissue located in the back of the inner eye that converts light
images to nerve signals and transmits them to the brain. There are receptor cells all
around the retina, these are the rod cells and the cone cells.
The rods are more numerous, some 120 million, and are more sensitive than the cones.
However, they are not sensitive to color. The 6 to 7 million cones provide the eye's color
The cones are less sensitive to light than the rods. The cones are responsible for all
high-resolution vision.
The density of receptor cells on the retina is greatest at the center and lowest at the
6. Question:
a. How does the anatomy of the eye affect peripheral vision?
7. Train Your Peripheral Vision:
a. Materials: straw and two toothpicks.
Your central vision, also known as foveal vision, is incredibly sharp and focused. That’s because
there are more rods and cones in the center of your retina. Plus, those ocular rods and cones are
far more sensitive to light.
As you start moving to your near, mid, and far peripheral vision, things start to get a bit hazier.
Thus, you’re typically not able to make precise movements or make out finer details. The straw
and toothpick exercise aims to change that.
Start by drawing a black line on the center of the straw with a marker. This line should go
around the circumference of the straw. When you set the straw horizontally on a flat
surface, the mark should appear as a vertical line that runs around the entire straw. Think
of it like a crosshair.
Now, have a friend hold that straw horizontally in their hands in front of you. Take a step
back so that you’re 1-2 feet away from the straw.
With a toothpick in each hand, focus your central vision on that black line. Now, try to
place the toothpicks into each end of the straw. While you’re doing this, keep your central
vision focused on that line!
As you continue to perform this exercise, you should train your mind to have a sharper
focus on your peripherals. Eventually, you’ll be able to place those toothpicks into the
straw without any issues.
Day 7: Vision Differences
Near/Far Sighted
Color Blindness
a. What is 20/20 Vision?
b. What else is there?
Activity: Vision Test
Share Lenses and Vision Diagram
Define in journals:
a. Near sighted
b. Far sighted
Share Song - Okee Dokie Brothers “Colors”
a. How do we know someone else see’s the same color that we do?
Review rods and cones
Activity: Color Blindness Tests
Discuss/Info: How other animals see colors/rods/cones
Day 8: Blindness/Helen Keller
1. Discuss what blindness is
2. Read about Helen Kellar
3. Make braille nametag
Day 9: Optical Illusions
1. Share optical illusions
2. Discuss what’s happening
3. Magic eye books
Day 10: Pre Lab
1. Discuss meaning/purpose of dissections, how they are used
a. Link to Galen
2. Discuss animal eyes
3. Show prelab video
4. Show equipment and discuss expectations
Day 11: Sheep Eye Dissection
1. Sheep eye dissection
2. Make mat for students to place parts