Click "Print Lesson" button to use your browser print Student Name: Alethea
Date Printed: Jan 11, 2015
Science 3
Unit 9: Light
Lesson 1: Traveling Light
Duration: Approx. 60 min.
There are one or more assessments in this lesson. Offline assessments and answer keys can be printed from the materials lists. Online assessments must be printed from the assessment itself within the lesson.
Firefox cannot print Flash images. The on-screen images might print as blank spaces. If you need to print this lesson, try using Internet Explorer so that all the images print.
For the Adult
*clay, oil-based modeling
*lamp
*ruler
*oil, cooking
*matches
*candle - small
*CD case - plastic
*water
*paper, 8 1/2" x 11"
*paper towels, roll
*glass, drinking - clear
Investigation: Tricky Candle
1 day
Be sure to have a piece of a piece of plastic, preferably a CD case, for the activity.
Lesson 1: Traveling Light
| | absorb |
| Take in, but not let out. Like a sponge absorbing water, some things absorb light. A very black object absorbs most of the visible light that hits it. |
| light | |
| A natural or artificial form of energy that allows us to see. His friend's new bicycle was much easier to see in the light of day than it had been at night. |
| | opaque [oh-PAYK] |
| Not allowing light to pass through, so that objects behind something opaque cannot be seen. He wanted to have an opaque door so that someone outside his room could not easily tell if his light was on. |
| reflect | |
| Bounce off a surface, as light off a mirror. A perfect mirror reflects all the light that hits it, so that light starting out in one direction can end up going in quite another. |
| | translucent [trans-LOO-snt] |
| Allowing only some light to pass through, and scattering light that does, so that forms behind something translucent cannot be clearly seen. The sunlight passing through the translucent leaves provided enough light for his walk in the woods, even though he couldn't see anything in the sky. |
| transmit | |
| Pass through. A transparent object transmits all the light that hits it. |
| | transparent |
| Allowing almost all light to pass through, so that objects behind something transparent can be clearly seen. After his brother cleaned the window, it was so transparent that you could hardly tell it had glass in it. |
Investigation: Tricky Candle
Be sure to keep the matches out of your student's reach. Do not leave your student unattended with the lighted candle.
This activity is best completed online.
| Light is amazing. Without it, we wouldn't be able to see anything around us. Explore how our world would be different if there were no light. See how light can pass through, be reflected, or be absorbed by an object. | | |||||||
| Lesson Overview
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This activity is best completed online.
| Light Sources What is one difference between a window, a leaf, and a metal spoon? Light behaves differently when shining on them. Find out what it means to be transparent, translucent, or opaque. Which do you think you are? | |||||||||
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| Picture what things would be like if suddenly there were no light. How would the world look, in your mind? It wouldn't look like nighttime, because at night the stars still give off light. In fact, it wouldn't look like anything. Everything you have ever seen, you have seen because of light. With no light we would have nothing to eat. Why? There would be no sunlight for plants to make their own food. Animals that eat plants would starve. Then animals that eat those plant eaters would also starve. And without the sun, our planet would grow colder. . . and colder! Fortunately for all living things, light from the sun is plentiful. Light from the sun heats up our planet, lets plants make food, and lets you see where you are. Light lets our planet live. | |
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| Light is a curious thing, but one way to think of it is as bundles of energy. For example, you know that all matter is made of particles called atoms. Atoms have a certain amount of energy in them. Sometimes an atom will give off some of its energy in a tiny bundle. These bundles are what we call light. The scientific name for these bundles of energy is photons. Photons travel incredibly fast--as fast as scientists think anything can go in our universe. When you turn on a light in a dark room, it seems you can see everything at the very same time that you flipped the switch. In reality there is a small wait between the moment when the light bulb sent out some photons and the moment when those photons hit your eye. But light travels so fast it will always seem to happen at the exact same time. Try it and see. | |
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Answer(s):
[1]
Stars are so far away that scientists use the distance light travels in a year as the way to measure their positions. The distance light travels in a year is called a light-year and is about 9.46 trillion kilometers (or about 5.9 trillion miles; a trillion is a million millions.) The closest star to our sun is 4 light year away and many stars are million of light-years distant.
| Unlike fireflies and glow worms, most objects don't make their own light. So how can you see what's around you? It's because light from somewhere else bounces off objects before it enters your eyes. When light bounces off an object, we say it is reflected. When light strikes an object, three things can happen. It can be reflected, it can pass through (be transmitted), or it can be absorbed. Light can pass easily through gases such as air, and liquids such as water. It can even go through some solids, such as glass. Light can also travel through empty space. How can you tell light travels through space? [1] When light is absorbed, its energy is often changed to heat. Watch a representation of this in the "absorption" animation (number 3). | |
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Answer(s):
[1]
[1] If light didn't travel through space, we would not be able to see stars or the moon at night. Indeed, we wouldn't be able to see the sun in the day, either!
| Light reflects off smooth and bumpy surfaces differently. You can see this with two pieces of aluminum foil, one smooth and the other wrinkled. Look into a smooth piece of foil. Can you see your reflection? Now look into the wrinkled piece. What can you see? | | |
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| The smooth piece of foil acts like a mirror. When light bounces off of it, the light reflects back to your eyes in an orderly way. In other words, light from different places reflects back from the object in the same order it originally hit the object, forming a pretty clear image. Light from the boy's nose hits his eyes only from the middle of the foil. When it bounces off the bumps in the wrinkled foil, though, light goes off in many different directions. The reflection you see is fuzzy. It is as if the light is reflecting off lots of tiny mirrors, all facing slightly different directions. Light from the boy's nose hits his eyes from all over the foil, maybe not from the middle. | | |
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| Light can pass almost straight through a smooth pane of glass. Such a material is transparent. But a leaf, or a lampshade, is translucent. Translucent objects allow some light to pass through, but not all of it --you can see light shining through a leaf. Anything you can partly see through, such as honey, is translucent. Opaque matter, such as a wooden table or a metal spoon, blocks light altogether. Opaque objects make shadows with sharp edges. An opaque material does not allow any light to pass through it, but either reflects it or absorbs it. Or, possibly, both--it may reflect some and absorb some. | |
This activity is best completed online.
SAFETY: Be sure to keep the matches out of your student's reach. Do not leave your student unattended with the lighted candle.
| Tricky Candle It is fun to play with light. Try this activity to see the amazing things that can be made with a candle and a transparent object. Print the Tricky Candle activity sheet if you have not done so already. Follow the activity instructions to complete this activity. |
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Lesson Assessment: Traveling Light
This assessment is best completed online, where it will be automatically scored by the computer. If you would like to print it, do so from the assessment itself within the lesson.
This activity is best completed online.
| Presto Change! Can an object's translucency be changed? Find out using a piece of paper and a drop of oil. |
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Answer(s):
[1]
For fun and to further demonstrate reflection of light, go to Activity Resources and click on the Ray Optics, Light Reflection, More Rays website. When you get to the website, read the directions underneath the diagram and allow your student to explore reflection of light as it hits a mirror.
| You have learned that objects can be transparent, translucent, or opaque. But can an object change from being opaque to translucent or from translucent to transparent? Try this quick activity to see if it can. Place a drop of oil onto a piece of white notebook paper. Wipe off the extra oil using a paper towel. Shine a lamp onto the piece of paper as you look at the spot of oil. Does it look darker or lighter than the rest of the piece of paper? [1] Now hold the paper up between the lamp and your body. Which looks darker now, the paper or the spot of oil? [2] |
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Answer(s):
[1]
[1] darker
[2] the paper
[2] the paper
| Why did this happen? The piece of paper is made up of many fibers and pockets of air. Both the fibers and pockets are transparent by themselves. However, when they are combined, the light bends around inside and much is reflected back. This makes the paper more opaque than translucent. When you add the spot of oil, it fills the air spaces between the paper fibers. Then, the light from the lamp has a more even surface to pass through, so the light goes through straighter. When the light shines on the side of the paper facing you, most of the light from the dry paper is reflected back to your eyes, as before. But where the oil is, the light goes through, so that spot looks darker. When the light shines on the other side of the paper, more light passes through the paper where the oil is, making it look brighter than the rest of the paper, where the light is more blocked. |
Click "Print Lesson" button to use your browser print Student Name: Alethea
Date Printed: Jan 11, 2015
Science 3
Unit 9: Light
Lesson 2: Colors of Light
Duration: Approx. 60 min.
There are one or more assessments in this lesson. Offline assessments and answer keys can be printed from the materials lists. Online assessments must be printed from the assessment itself within the lesson.
Firefox cannot print Flash images. The on-screen images might print as blank spaces. If you need to print this lesson, try using Internet Explorer so that all the images print.
For the Adult
*paper, 8 1/2" x 11" - white (4)
*bowl
*ruler
*markers
*poster board, white
*water
*flashlight (2)
*clay, oil-based modeling
*pencil
*paper, construction - black
*tape, clear (2)
*battery - flashlight (3)
*scissors (2)
*mirror, hand
*plastic wrap, clear - red, blue, and green
*string
Investigation: Color Combinations
1 day
In this science activity, you will need three flashlights. Your student will also need to cover the flashlights with something to make red, green, and blue light. You can use clear, colored report covers, or colored plastic wrap. The colored plastic wrap produces the best results in this experiment.
Lesson 2: Colors of Light
| | opaque [oh-PAYK] |
| Not allowing light to pass through, so that objects behind something opaque cannot be seen. He wanted to have an opaque door so that someone outside his room could not easily tell if his light was on. |
| | translucent [trans-LOO-snt] |
| Allowing only some light to pass through, and scattering light that does, so that forms behind something translucent cannot be clearly seen. The sunlight passing through the translucent leaves provided enough light for his walk in the woods, even though he couldn't see anything in the sky. |
This activity is best completed online.
| Is an apple really red, and is the sky really blue? The light shining from a white light bulb may look like one color, but it really holds all the colors of the rainbow. Explore how light can be separated into many colors and mixed together to become white. | | |||||||||
| Lesson Overview
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This activity is best completed online.
| The Colors of Light Have you ever seen a purple banana? How about a blue apple? Probably not. See why bananas are yellow and why apples are not blue as you explore the wonders of light. | |||||||||
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| Have you ever watched rays of sunlight shining in through a window or down through a cloud? A ray of light can be thought of as a stream of tiny particles of energy that move like baseballs continually shooting out of a pitching machine. These little particles of light energy are called photons. But you can’t see individual photons as objects. They are much too small and move much too fast. What you see as a ray of sunlight is really light scattered off the dust in the air. Light acts as little particles of energy when it strikes a surface. Light can reflect off objects like balls bouncing off a wall. Light can pass straight through transparent objects, such as a windowpane, like balls going right through an open hole. Light can be absorbed, like balls sticking to a soft clay wall. Opaque objects, such as wood or metal, completely block light by reflecting and absorbing it. When light hits translucent objects, such as wax paper, some scatters, some is reflected, some transmitted, in different directions. Some may even be absorbed, too. | |
| Light travels at slightly different speeds in different types of transparent matter. When photons move from air to water, for example, they slow down. When they pass back to the air they speed up. But you can't really see light changing speed the same way you can a car. This is because you can't see individual photons as objects, because they already travel so fast, and the changes in speed are very small. Unless you use special equipment, you can't even measure the speed of light, much less tell that the light is changing speed. But you can see the results in other ways. | |
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Answer(s):
[1]
Light entering or exiting a substance "at an angle" means it's not moving "straight on", or perpendicular to the surface, but is sideways to a degree.
A good analogy would be a ball bouncing off a surface. If the ball moves "straight on" to a surface, the ball would bounce back along the same path it used getting to the surface. It bounces straight back up.
The direction "at an angle" is like one in which the ball is thrown sideways against the surface, to bounce away in a different direction from the one through which it arrived.
A good analogy would be a ball bouncing off a surface. If the ball moves "straight on" to a surface, the ball would bounce back along the same path it used getting to the surface. It bounces straight back up.
The direction "at an angle" is like one in which the ball is thrown sideways against the surface, to bounce away in a different direction from the one through which it arrived.
| As light enters or exits an object at an angle, the changes in speed make the light bend, or refract. See how the ruler in the picture looks bent at the surface of the water? When the light particles from the ruler speed up as they move from the water into the air, they change direction. They refract. | |
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Answer(s):
[1]
Light entering or exiting a substance "at an angle" means it's not moving "straight on", or perpendicular to the surface, but is sideways to a degree.
A good analogy would be a ball bouncing off a surface. If the ball moves "straight on" to a surface, the ball would bounce back along the same path it used getting to the surface. It bounces straight back up.
The direction "at an angle" is like one in which the ball is thrown sideways against the surface, to bounce away in a different direction from the one through which it arrived.
A good analogy would be a ball bouncing off a surface. If the ball moves "straight on" to a surface, the ball would bounce back along the same path it used getting to the surface. It bounces straight back up.
The direction "at an angle" is like one in which the ball is thrown sideways against the surface, to bounce away in a different direction from the one through which it arrived.
| Photons act like waves--similar to the ripples in a pond--as well as like particles. The distance between the waves is their wavelength. Visible light, X-rays, and ultraviolet rays (UV rays--the kind that can give you a sunburn) are three types of energy the sun gives off. Their main difference is in their wavelengths. We cannot see X-rays or UV rays, which have shorter wavelengths. Visible white light is a mixture of all the colors in the rainbow, each with its own wavelength. A prism--a specially shaped piece of glass--can separate light into the colors of the rainbow. Each color of light bends at a different angle as it moves through the prism. The shorter wavelengths, at the violet end, refract at a larger angle than longer ones, at the red end. The band of colors refracted by a prism is called the visible spectrum. | |
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Answer(s):
[1]
You can see the visible spectrum in a rainbow because the tiny drops of water in the air act like tiny prisms to refract sunlight.
| Now you know that sunlight is a mixture of all the colors. But what does light have to do with the fact that grass is green, the sky is blue, apples are red, and the morning newspaper is black and white? Grass in itself is not green on the inside. It looks green because it absorbs all the colors of light except green. The grass reflects any green light striking it back to your eyes. Objects reflect the colors of light that we see, and they absorb the rest. So what colors does a newspaper reflect? Remember that white light is a mixture of all the colors of light. The white part of the page reflects all the colors, so we see the page as white. The black ink absorbs all the colors and reflects none, so the letters appear black. Things look black when they reflect little or no light. | |
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Answer(s):
[1]
Clouds look white because the water droplets and ice crystals that make them up scatter all the colors of light, and white light is a mixture of all the colors.
[2]
Have your student find objects around him and identify the colors they reflect.
| You may have heard of primary colors. You mix them to get the other colors. Red plus yellow, for example, makes orange. What are the three primary paint colors? [2] You can also make any color of light by mixing primary colors. But light is different. Its primary colors are red, green, and blue. When you mix red and green light you get yellow light. But if you mix red and green paint, you get brown paint. The difference is that paints absorb light. A mixture absorbs all the colors the paints in it absorbed. You don't see those colors. What do you get when you mix all three primary colors, and why? [3] When you mix light, you add the colors they send out, the colors you do see. What do you get when you mix all three primary colors of light, and why? [4] | |
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Answer(s):
[1]
[2] red, yellow, and blue
[3] black or brown, because most of the colors are absorbed, little is reflected
[4] white light, because white light is a mixture of all the colors of light
[3] black or brown, because most of the colors are absorbed, little is reflected
[4] white light, because white light is a mixture of all the colors of light
[2]
Mixng different amounts of the three primary colors of light produces all the colors on your television or computer screen. In fact, that's what lets you see white there as well. Little dots of red, green, and blue light blend together to make white light.
| Refraction is the bending of light as it travels from one type of matter to another--for instance, from air to water. Refraction separates the colors of light. Filters can also separate colors of light. For example, red cellophane or red gelatin acts as a filter for red light. If you shine white light through a red filter, the red light passes through but the filter absorbs all the other colors. Objects can look quite different in different colors of light. Have you ever looked through a pair of yellow, blue, or green sunglasses? Sunglasses are light filters. The Earth's atmosphere also acts as a natural light filter. The atmosphere reflects blue and violet light more than the other colors, scattering it in all directions. So the longer wavelengths go more directly through, but the blue goes all over the place, filtered out of the direct path. When you're looking at the light coming indirectly from the sun from around the sky, the sky looks blue. | |
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Answer(s):
[1]
Explain to your student that refraction can take place when light photons move from air to water, whereby the light photons slow down. When the light photons pass back to the air they speed up. This change in speed of photon movement causes the light to bend, or refract.
This activity is best completed online.
| Rainbow Colors Have you ever seen a rainbow up close? Light may look clear, but it is really made up of red, orange, yellow, green, blue, indigo and violet all mixed together. Make a rainbow that is close enough to touch. Print the Splitting Light activity sheet if you have not done so already. Follow the activity instructions to complete this activity. |
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This activity is best completed online.
| Color Combinations You have learned how to separate white light into colors. What do you think will happen when you mix colors together? |
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Answer(s):
[1]
Combining colors of light and combining colors of the pigment found in paints are not the same. The primary colors of pigment are different from those of light. The primary colors of pigment are red, blue, and yellow, not red, blue, and green. Use the flashlights from this activity with some paint and see the differences for yourself.
- Use a paintbrush to mix the same amount of red and green paint on a piece of white paper.
- Then shine the flashlights covered in the red and green plastic wrap on the same spot of a different piece of white paper.
- Compare the shades that you get when you combine green and red paint to the one you get when you combine red and green light. Are they the same?
- Repeat steps 1-3 with red and blue, and blue and green.
Lesson Assessment: Colors of Light
Print this offline assessment and answer key using the links below. You will need to enter your student's results online later.
This activity is best completed online.
| Color Wheel Can your brain be tricked into seeing or not seeing certain colors? This colorful experiment will amaze you! |
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| See if you can trick your brain with this fun experiment. Activity Steps
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Click "Print Lesson" button to use your browser print Student Name: Alethea
Date Printed: Jan 11, 2015
Science 3
Unit 9: Light
Lesson 3: Light Energy
Duration: Approx. 60 min.
There are one or more assessments in this lesson. Offline assessments and answer keys can be printed from the materials lists. Online assessments must be printed from the assessment itself within the lesson.
Firefox cannot print Flash images. The on-screen images might print as blank spaces. If you need to print this lesson, try using Internet Explorer so that all the images print.
For the Adult
*thermometer
*lamp
*paper, construction - white
*paper, construction - black (2)
*water
*aluminum foil
*plastic bags - zipper closed (2)
*can, tin - empty (2)
*ice
Investigation: Heat It Up!
1 day
A lamp will be used in the experiment so leave one on for ten minutes to warm up. Note: The lamp must provide sufficient heat for the experiment. If you can, find the type of bulb, of any wattage, that will provide the heat. If you cannot find one bulb that will heat efficiently, try arranging a number of bulbs until the experiment works. Be creative in finding a heat source that does the job. You will also need two empty tin cans.
Lesson 3: Light Energy
| | translucent [trans-LOO-snt] |
| Allowing only some light to pass through, and scattering light that does, so that forms behind something translucent cannot be clearly seen. The sunlight passing through the translucent leaves provided enough light for his walk in the woods, even though he couldn't see anything in the sky. |
This activity is best completed online.
| Have you ever noticed that many people wear bright colors in the summer and darker colors in the winter? Explore how the darkness of the color affects how much light energy is absorbed, as well as how light energy can be converted into heat energy. | | |||||||
| Lesson Overview
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This activity is best completed online.
| Light Energy Why does a dark red tee-shirt absorb more light energy than a bright red tee-shirt? Review light from the previous lesson and discover how dark colors absorb more light energy and light colors absorb less. | |||||||||
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| Light can zoom through empty space, such as the space between the sun and the Earth, as well as through substances such as air and glass. It bounces off other materials, reflected from one place to another. This is good because we see objects by the light they reflect. Most objects don't reflect all the light that hits them. They absorb some parts of the light and reflect others. An object's color depends on what parts of the light it reflects. In white light grass looks green, the color it reflects. A robin's egg looks blue, because that's the color it isn't absorbing--which is why it bounces from the egg to your eyes. Why is a tomato red? [1] Some things make their own light, such as a firefly, a light bulb, or a TV. When the TV is turned off, though, all you see is reflected light. | | |
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Answer(s):
[1]
[1] Because it reflects red light and absorbs blue and green light.
| Remember that light is a form of energy. When light hits something it can be reflected, transmitted or absorbed. If it’s reflected, the energy goes off in a new direction, like a ball bouncing off a wall. If it’s transmitted, the light goes right through the object, like the ball going through a hole in the wall instead of bouncing back. White objects reflect all the colors of light--that’s why they look white. They send most of the light energy that comes their way bouncing back again. Transparent objects let the light, and its energy, go right through them. What do you think happens to the energy when light hits a black object, which absorbs all the colors? [2] | |
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Answer(s):
[1]
[2] It absorbs the energy of the light.
| Of course, not everything is black, white, or transparent. Most things are colored--that is, they reflect some, but not all, of the light that hits them, and they absorb some. They can be darker or lighter versions of colors. They can even be colored but translucent, like a stained glass window. Since white is what we see when all the colors are reflected back, it’s no surprise that black is what we see when no colors are reflected at all. If black objects aren’t reflecting much light, though, they must be absorbing lots, with its energy. Can you see, then, that darker-colored objects absorb more energy than lighter-colored objects? A dark red sweater absorbs more light energy than a light red sweater, which reflects more energy back. | |
| You already know that energy is not created or destroyed, but changes forms and moves around. What becomes of the energy in light, then, when it is absorbed? It must be transferred somehow to the material that absorbs it. And this is just what happens! One way energy in light transfers is by speeding up the molecules of the object, which means the object heats up. Look at the screen. As the dark purple shirt sits in the sun, its molecules are more excited, and it becomes warmer than the brighter shirt. The energy from the absorbed light changes into heat energy. | |
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| Let’s review. When light is absorbed, its energy is transferred to whatever absorbs it. Often that light energy is changed to heat energy. Light that is reflected carries its energy away with it. Light that passes right through an object, such as a sun beam passing through a window, carries its energy with it as well. Also, energy is neither created nor destroyed. It always comes from somewhere and goes somewhere else. The more light that is transmitted through something, or reflected off it, the less light that same something will absorb. And that often means the less that same something will heat up. | |
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Answer(s):
[1]
Challenge question for your student.
If a red light and a white light both carry the same amount of energy, which one will make a red sunshade hotter?
Answer
The white light will. The red sunshade reflects red light, and absorbs the energy of other colors of light. Red is only a small component of the white light, and so most of the white light energy is absorbed by the sunshade. When you only shine red light on the sunshade, more of the light energy is reflected.
If a red light and a white light both carry the same amount of energy, which one will make a red sunshade hotter?
Answer
The white light will. The red sunshade reflects red light, and absorbs the energy of other colors of light. Red is only a small component of the white light, and so most of the white light energy is absorbed by the sunshade. When you only shine red light on the sunshade, more of the light energy is reflected.
| So, now that you know about some of the things light does, answer this. Two cats are sitting in a sunny window. One has black fur and the other has light-colored fur. Which one’s fur will get warmer, faster? [3] Why? [4] | |
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Answer(s):
[1]
[3] The black cat's fur will get warmer faster.
[4] The dark color reflects less light--that’s why it appears dark. Since it isn’t reflecting light, it must be absorbing it instead. And since it is absorbing more light energy, more of that energy will be converted to heat energy than in the light-colored fur.
[4] The dark color reflects less light--that’s why it appears dark. Since it isn’t reflecting light, it must be absorbing it instead. And since it is absorbing more light energy, more of that energy will be converted to heat energy than in the light-colored fur.
[2]
Challenge question for your student.
If a red light and a white light both carry the same amount of energy, which one will make a red sunshade hotter?
Answer
The white light will. The red sunshade reflects red light, and absorbs the energy of other colors of light. Red is only a small component of the white light, and so most of the white light energy is absorbed by the sunshade. When you only shine red light on the sunshade, more of the light energy is reflected.
If a red light and a white light both carry the same amount of energy, which one will make a red sunshade hotter?
Answer
The white light will. The red sunshade reflects red light, and absorbs the energy of other colors of light. Red is only a small component of the white light, and so most of the white light energy is absorbed by the sunshade. When you only shine red light on the sunshade, more of the light energy is reflected.
This activity is best completed online.
| Heat It Up! Can the color of an object affect its ability to heat up? Use cans of water covered with colored paper and a lamp to find out. Print the Heat It Up! activity sheet if you have not done so already. Follow the activity instructions to complete this activity. |
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Lesson Assessment: Light Energy
Print this offline assessment and answer key using the links below. You will need to enter your student's results online later.
This activity is best completed online.
| It's Melting! You have learned that a dark-colored surface will absorb more light than a light-colored surface. What about a shiny surface? Will it absorb more light energy than a dark-colored surface? Use ice cubes and aluminum foil to find out. Follow the activity instructions to complete this activity. |
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Click "Print Lesson" button to use your browser print Student Name: Alethea
Date Printed: Jan 11, 2015
Science 3
Unit 9: Light
Lesson 4: Vision
Duration: Approx. 60 min.
There are one or more assessments in this lesson. Offline assessments and answer keys can be printed from the materials lists. Online assessments must be printed from the assessment itself within the lesson.
Firefox cannot print Flash images. The on-screen images might print as blank spaces. If you need to print this lesson, try using Internet Explorer so that all the images print.
For the Adult
*paper, 8 1/2 x 11" - white
*magnifying glass
*ruler, metric
*household item - television set
Beyond The Lesson: A Closer Look at the Eye
1 day
Websites and books: As usual, you may wish to preview any books or websites listed in this lesson.
Lesson 4: Vision
| | Braille [brayl] |
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| cones | |
| Special light-sensitive cells that allow us to see colors and fine detail. Cones are not as sensitive to light as rods, so they need bright light to work well. |
| cornea | |
| The transparent part of the eye that covers the pupil and the iris. |
| iris | |
| The colored part of the eye surrounding the pupil. |
| lens | |
| A transparent structure behind the pupil, with curved surfaces, thicker in the middle than at the edges, that bends light entering the eye to help form images on the retina. |
| pupil | |
| The opening in the eye through which light enters. |
| | retina [REH-tn-uh] |
| The layer at the back of the eye where light-sensitive cells are found. |
| rods | |
| Special light-sensitive cells, very sensitive even in dim light. Rods help us see in very dim light, but only in black and white. They are not involved in our seeing of colors or fine detail. |
| | sclera [SKLEHR-uh] |
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Beyond The Lesson: A Closer Look at the Eye
As usual, you may wish to preview any books or websites listed in this lesson.
This activity is best completed online.
| Do you enjoy watching the explosion of colors during a fireworks display or in a field of beautiful flowers? You can thank your eyes for that. The eye is an amazing organ with many different parts working together to help us see. Learn about the different parts of the eye and how each part has its own special job. | | |||||||||
| Lesson Overview
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This activity is best completed online.
| The Amazing Eye How does our sense of vision really work? How does our brain make sense of it all? Believe it or not, scientists are still studying these questions. But let’s find out what we do know about the parts of our eyes that help us see. | |||||||||
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| What a wonderful thing it is to have eyes. With them we can see the sky lighting up orange and gold and tiny blue flowers in a meadow. Our eyes are important sense organs. We rely on them first to tell us much of what we can learn about the world. They can see the friend standing next to us as well as the one waving her arms on top of a hill. We can see both the candle burning brightly and the dim light of a distant star. And, with telescopes or microscopes, we can even see things too small or too far away to make out otherwise. But how does vision work? How do our eyes use light to see objects? How does our brain make sense of it all? Scientists are still working on these questions. Let's learn about what is known. | |
| Light enters your eye through your pupil. Your pupil is the opening in the center of your eye. It's surrounded by a colored circle called the iris. The white part of your eye is the sclera (SKLEHR-uh). Even though your pupil is an opening, it looks black. Why do you think that is so? [1] Your iris has sets of muscles that can adjust the size of your pupil to let in just the right amount of light. Think back to what you know about the muscular system. When it is very bright out, involuntary muscles in your irises contract, or shorten, to make your pupils smaller. This keeps your eyes from getting too much light. In dim light, another set of muscles contracts and your pupils get larger. That lets more light into your eye when it needs more light to see. | |
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Answer(s):
[1]
[1] All the colors of visible light pass through the pupil and are absorbed by the eye.
| Vision is the ability of our eyes to make an image from light that has bounced off an object--and of our brains to make sense of that image. Aha! That's a toaster. And that's a cereal bowl. And that’s a spoon. After entering through the pupil, light is focused on the back of your eye. The back of your eye is covered with light-sensitive cells. They change the light energy into electrical signals. These go to other cells in your eye and then are sent on through nerves to your brain, which makes sense of them. Let's take a closer look at the different parts of the eye. We'll learn more about how the information carried by light travels through your eye and to your brain. | |
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| Your iris and pupil are covered by a clear tissue called the cornea. This protects them. Your cornea and your sclera--the white part--are connected like one piece, but it's clear over your iris. Behind your pupil and iris is your lens. Your lens is about the size of a lima bean, and bends light rays to focus the image on the back of your eye. The back of your eye is called the retina (REH-tn-uh). Between your lens and the back of your eye is a clear, jelly-like substance that lets the light rays pass through it. | |
| There are two main kinds of cells in the retina for sensing light. These cells, called rods and cones, are actually special kinds of nerve cells. They are called rods and cones because that’s how they are shaped. Rods are long and thin, while cones are wider at one end than the other. Cones are mostly in the center of the retina, so the sides of the retina have mostly rods. | |
| Cones let you see colors, as long as there is bright, strong light. They also let you see clear, sharp images with a lot of small details. There are actually three types of cones. Each type is more sensitive than the others to one of the three primary colors. What are the three primary colors of light? [2] | |
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Answer(s):
[1]
[2] red, green, and blue
[2]
Blind spotThere are no rods or cones at the point where the optic nerve leaves the retina. When the image of an object falls on this "blind spot," you can't see the object.
To test your blind spot, place two dots 13 cm apart on a piece of paper. Hold the paper about 30 cm from your face. Close your left eye and look at the left dot. Slowly move the paper in and out. The right dot will disappear when its image falls on the blind spot.
To test your blind spot, place two dots 13 cm apart on a piece of paper. Hold the paper about 30 cm from your face. Close your left eye and look at the left dot. Slowly move the paper in and out. The right dot will disappear when its image falls on the blind spot.
| Rods, on the other hand, aren't sensitive to color. They produce kind of blurry, black and white images. Is that a bad thing? Not at all--rods are more sensitive to dim light, so are better at night, when cones aren't very useful. Both rods and cones are important to how we see. Rods and cones change light energy they receive to electrical signals that are passed first to other nerve cells, then into the optic nerve. The optic nerve carries the signals to your brain, which makes sense of them. | |
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Answer(s):
[1]
Blind spot
There are no rods or cones at the point where the optic nerve leaves the retina. When the image of an object falls on this "blind spot," you can't see the object.
To test your blind spot, place two dots 13 cm apart on a piece of paper. Hold the paper about 30 cm from your face. Close your left eye and look at the left dot. Slowly move the paper in and out. The right dot will disappear when its image falls on the blind spot.
There are no rods or cones at the point where the optic nerve leaves the retina. When the image of an object falls on this "blind spot," you can't see the object.
To test your blind spot, place two dots 13 cm apart on a piece of paper. Hold the paper about 30 cm from your face. Close your left eye and look at the left dot. Slowly move the paper in and out. The right dot will disappear when its image falls on the blind spot.
| Let's review the path light travels from your eye to your brain. First, it goes through your cornea. Because your cornea is curved, light may pass through it at an angle, and refract, or bend, towards the center of the eye. Then it goes to your pupil. The iris adjusts the pupil's size to control the amount of light that gets through. Then the light goes to the lens. As the light rays pass through the lens they refract towards each other. After they pass through the clear jelly-like substance inside of the eye, the light rays meet, or focus, on the retina at the back. That's where the rods and cones are. Rods and cones convert the light energy to electrical signals that are sent to other cells, then through the optic nerve, to the brain. | |
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Answer(s):
[1]
The image formed on the retina is upside down. What you see, though, is the result of how your brain handles the information it gets from your eyes. It doesn't matter that it's upside down because the brain "knows" how to make it useful to you.
This activity is best completed online.
| The Parts of The Eye There are many different parts to the eye. Review where they are located by labeling an illustration of the eye and describing the functions of each labeled part. Print the Parts of the Eye activity sheet if you have not done so already. Follow the activity instructions to complete this activity. |
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This activity is best completed online.
| Topsy Turvy T.V. Wouldn't it be fun to watch the T.V. upside down? See what it's like as you explore how the lens in your eye bends light rays to focus an image on your retina. Print the Topsy Turvy activity sheet if you have not done so already. Follow the activity instructions to complete this activity. |
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Lesson Assessment: Vision
Print this offline assessment and answer key using the links below. You will need to enter your student's results online later.
This activity is best completed online.
SAFETY: As usual, you may wish to preview any books or websites listed in this lesson.
| A Closer Look at the Eye Learn more about the eye as you watch a virtual dissection of a cow's eye. | |||||||||||
| Safety As usual, you may wish to preview any books or websites listed in this lesson. | ||||||||||
| Visit the Cow Eye Dissection website to enter an online dissection of a cow's eye. |
Click "Print Lesson" button to use your browser print Student Name: Alethea
Date Printed: Jan 11, 2015
Science 3
Unit 9: Light
Lesson 5: Light: Unit Review and Assessment
Duration: Approx. 60 min.
There are one or more assessments in this lesson. Offline assessments and answer keys can be printed from the materials lists. Online assessments must be printed from the assessment itself within the lesson.
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For the Adult
*cellophane, colored
*pencil
*paper, construction - white
*bowl
*paper, construction - black
*mirror, hand
*flashlight
*water
Investigation: Light Show
1 day
Invite friends and/or family to the Light Show. Reuse the printouts from previous activities titled Splitting Light, Combining Colors of Light, and Topsy Turvy.
Explore: Scavenger Hunt!
Accompany your student when he goes outside. Never leave him unattended outside.
This activity is best completed online.
| You have seen a number of interesting things in this unit--thanks to light. Prepare to take the unit assessment by putting on a Light Show and reviewing all the things you have learned. | | |||||
| Lesson Overview
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This activity is best completed online.
SAFETY: Accompany your student when he goes outside. Never leave him unattended outside.
| Scavenger Hunt! Put your investigator hat on and let's review all the amazing things you learned about light energy. | |||||||||
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| Think how much you know about light. You’ve learned that you need light to see things with your eyes. You learned that light is a form of energy, and sunlight is the main source of energy for our planet. What do you think would happen to our planet if there were no sunlight? [1] When light strikes an object, three things can happen to the light. Can you name these three things? [2] Put your investigator hat on and look all around you. See if you can identify some objects that reflect, transmit (let pass through), or absorb light. | |
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Answer(s):
[1]
[1] Answers may vary, but might include some of the following. First, it would become very dark and cold very fast. Even if we could use energy sources already here to keep ourselves warm and provide some light, the plants would not have very much light to convert to chemical energy, which provides food for animals and us, and provides oxygen for animals and us to breathe. Therefore, we would be cold and eventually have no food to eat or oxygen to breathe. With no plants, animals that eat plants would starve and die. Then the animals that eat the plant eaters would starve and die.
[2] The light can reflect off the object, pass through the object, or be absorbed by the object.
[2] The light can reflect off the object, pass through the object, or be absorbed by the object.
| As light moves from one transparent or translucent environment to another, it either slows down or speeds up just a little bit, depending on the types of materials. If the light moves across the boundary at an angle, it bends or refracts as its speed changes. So refraction is a sign that light is slightly speeding up or slowing down. | |
| Light refracts as it passes at an angle in and out of different types of matter, such as air, water, or glass. What do you think happens to the speed of the light when the light moves from air to water? [3] What do you think happens to the speed when the light moves from water to air? [4] Do you think that light speeds up or slows down when it passes from glass to air? [5] From air to glass? [6] From hot air to cold air (hint: cold air is denser)? [7] | |
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Answer(s):
[1]
[3] Light slows down as it moves from air to water.
[4] Light speeds up when it moves from water to air.
[5] Light speeds up when it moves from glass to air.
[6] Light slows down when it moves from air to glass.
[7] Light slows down when it moves from hot air to cold air.
[4] Light speeds up when it moves from water to air.
[5] Light speeds up when it moves from glass to air.
[6] Light slows down when it moves from air to glass.
[7] Light slows down when it moves from hot air to cold air.
| You've learned that white light is a mixture of all the colors of visible light. These colors are called the visible spectrum. Just as paints have primary colors, light has primary colors. Primary colors in light are red, green, and blue, and they mix together differently than paint colors do. When you mix red and green light, for example, you get yellow light. What do you get when you mix all three primary colors of light? [8] | |
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Answer(s):
[1]
[8] white light
| You also learned something pretty amazing about light and colors. You found out that grass being green doesn't mean having green light inside. Grass looks green because grass reflects the green light back to your eyes and absorbs all the other colors, so you don't see them. All you see is the green light. Objects reflect some colors of light and absorb all the others. A red apple reflects one color and absorbs the rest. What color does it reflect? [9] | |
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Answer(s):
[1]
[9] red
| When light hits an object, it reflects, passes through, or is absorbed, depending on the type of material. For instance, a mirror, which has a smooth and shiny surface, reflects light evenly. The rough surface of a rock reflects light by scattering it in many directions. What other rough objects can you think of that might cause reflected light to scatter? The rock also absorbs some light. Have you noticed rocks getting hot in the sun? Now imagine walking barefoot on a dark surface, such as asphalt, on a hot summer day. Does the surface feel hot or cool? What if you were walking on a light surface, such as concrete? If possible, step outside on a sunny day and test your bare feet on these two surfaces, or on other dark and light surfaces. Which surface would you rather walk on in the summertime and why? [10] | | |
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Answer(s):
[1]
[10] The light surface. Sunlight reflects more off light surfaces, and dark surfaces absorb more sunlight. When a surface absorbs light, the light energy turns into heat energy, so dark surfaces heat up more than light surfaces.
[2]
If necessary, explain to your student that asphalt is the dark pavement on many streets.
Accompany your student outside to test the asphalt and concrete surfaces.
Accompany your student outside to test the asphalt and concrete surfaces.
| Vision is one of our most important senses. Each part of the eye--pupil, iris, cornea, lens, retina, optic nerve, rods, and cones--plays an important part in helping us see. The brain also plays a role in vision. Can you remember what your brain does to help you see? [11] How we see depends first on light energy entering our eyes carrying the information the eye will "tell" the brain. What do your eyes do with light energy? Let's do an experiment to see one thing they do with it. Gather a flashlight, a pen, and a piece of paper. Look at your eyes in a mirror and notice the sizes of your pupils. Now shine the flashlight on one eye for just a few seconds. Write down the changes you observed. [12] | |
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Answer(s):
[1]
[11] The brain interprets the patterns in the light that travels through the eyes.
[12] The pupil decreased in size, or contracted, when the light hit the eye. You may notice that the other pupil that did not get the extra light also contracted.
[12] The pupil decreased in size, or contracted, when the light hit the eye. You may notice that the other pupil that did not get the extra light also contracted.
| Your eyes have many parts, and each part plays a special role in helping you see. Your iris and pupil are covered and protected by transparent tissue called the cornea, which is continuous with the sclera--the white part of your eye. Just behind the pupil and iris is the lens. The lens bends, or refracts, light rays to focus the image onto the back of your eye. The back of your eye is called the retina. When light hits the retina, light energy is converted to chemical energy that then changes to electrical signals. The electrical signals pass on to other nerve cells, then to the optic nerve, which carries the signals to the brain. Look at the eye diagram onscreen and identify the various parts of the eye described above. | |
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Answer(s):
[1]
[13] What two specialized receptors in the retina are sensitive to light? (Hint: These cells are named after their shapes.)
[2]
[13] rods and cones
| Let's review how you see an object as light travels through your eye and your brain "reads" the light. On a piece of paper, draw a picture of how light travels from a light source through your eye, and write down as much detail as you can about what each part of your eye does to help you see. If necessary, review the screen 6 of 8 to help you create your drawing. You will want to make the picture large so you can draw each part of the eye clearly. To get started, first show how light from a source, such as a flashlight, passes through the transparent cornea. Now draw the path the light takes through the rest of the eye to the cells in the retina. | |
This activity is best completed online.
| Light Show Amaze your friends and family with all that you have learned about light. Gather them to watch your spectacular Light Show. Follow the activity instructions to complete this activity. |
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Unit Assessment: Light
Print this offline assessment and answer key using the links below. You will need to enter your student's results online later.
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