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Students will make simple adjustments to this noisemaker, you can raise or lower its pitch and make different kinds of sounds.

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By making simple adjustments to this noisemaker, you can raise or lower its pitch and make different kinds of sounds.

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You can watch the pupil of your eye change size in response to changes in lighting. You can also experiment to determine how light shining in one eye affects the size of the pupil in your other eye.

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The size of your pupils actually reflects the state of your body and mind. Pupil size can change because you are fearful, angry, in pain, in love, or under the influence of drugs. Not only does the pupil react to emotional stimuli, it is itself an emotional stimulus. The size of a person's pupils can give another person a strong impression of sympathy or hostility.

The response of the pupil is an involuntary reflex. Like the knee-jerk reflex, the pupillary response is used to test the functions of people who might be ill or injured. You may have seen a doctor shine light into the eyes of a person with a suspected head injury-they are looking at the pupillary response.

The pupil of your eye is also the source of the red eyes you sometimes see in flash photographs. When the bright light of a camera flash shines directly through the pupil, it can reflect off the choroid, which supplies red blood to the retina (the light-sensitive lining at the back of your eye), and bounce right back out through the pupil. If this happens, the person in the photograph will appear to have glowing red eyes. To avoid this, photographers move the flash away from the camera lens. With this arrangement, the light from the flash goes through the pupil at an angle, illuminating a part of the retina not captured by the camera lens. Many cameras are equipped with red-eye reduction features, such as a pre-flash that causes pupil constriction before the actual flash that illuminates the photo.

This Science Snack is part of a collection that highlights Black artists, scientists, inventors, and thinkers whose work aids or expands our understanding of the phenomena explored in the Snack.

Source: Wikimedia Commons

Dr. Patricia Bath (1942-2019), pictured above, was an ophthalmologist and laser scientist, and was the first woman chair of ophthalmology at a US university. She studied the causes of and cures for blindness, and invented a widely used method of using laser surgery to treat blindness caused by cataracts. Dr. Bath also co-founded the American Institute for the Prevention of Blindness. This Science Snack can help you investigate the structures in the eye that help you see, so you can understand the eye like Dr. Bath did.

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The size of your pupils actually reflects the state of your body and mind. Pupil size can change because you are fearful, angry, in pain, in love, or under the influence of drugs. Not only does the pupil react to emotional stimuli, it is itself an emotional stimulus.

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Why do your pupils get bigger in the dark?

Where is the pupil?

What is the iris?

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Do you like to stay up late? Of course you do! Who doesn't like to extend their bedtime by a few minutes or even a few hours? It's only natural to want to keep the fun going when you're having a good day.

But are you a night owl by nature? Some people seem to function better later in the evening, while others tend to be the most productive during the day. If you've ever stayed up late at night with friends, you may have noticed something peculiar about their eyes. Have you ever noticed that your eyes seem to look bigger in the ?

If you've ever noticed this phenomenon, you're not just imagining things. A part of your does indeed get bigger in the . What are we talking about? The , of course!

To learn why this happens, we need to know a bit more about the itself. The outer part of your that you can see and feel is called the . Just behind the sits the , a circular membrane that gives your eyes their color.

The plays an important role in the proper functioning of the . Its job is to control the amount of light that enters the through your , which is the opening in the middle of the that looks like a black .

Why is this role so important? Like a camera depends upon light to capture images, your eyes depend upon the correct amount of light to see . During the day, less light is needed to see the things around you. At night, however, more light is usually needed to see things you might have seen easily during the day.

To control the amount of light entering the , the widens or narrows to change the size of the . For example, when it's , the widens and the dilates, or gets bigger, to allow as much light as possible to enter the .

The opposite occurs during the day. When the Sun is shining bright, the narrows and the constricts, or gets smaller. This restricts the amount of light entering the , allowing only enough light to see .

The amount of light can vary wildly throughout the day and into the night. Your pupils respond and react accordingly as light levels . The size of the can change in size from as little as 1.5 millimeters to over 8 millimeters in diameter.

In addition to controlling the amount of light that enters the , your pupils can also change size in response to . If you're or afraid or even in love, your pupils can change in size as your body feels these emotions.

Your pupils can also and as a result of a variety of medicines and drugs. In fact, doctors will often shine a light into a patient's eyes to test the reaction of the to determine whether the body appears to be functioning .

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Why Do Your Pupils Get Bigger in the Dark?

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Do you like to stay up late? Of course you do! Who doesn't like to extend their bedtime by a few minutes or even a few hours? It's only natural to want to keep the fun going when you're having a good day. But are you a night owl by nature?

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Students will be able to understand how energy is stored, released and transferred in a chain reaction machine.

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Description: Rube Goldberg machines are named after American cartoonist Rube Goldberg who drew complicated steps involved in doing a fairly simple task (like pouring milk in a glass). Students can study these machines, or build their own, to show how energy can be converted through a series of interactions. In lower elementary classes they might be shown or built to show how pushes or pulls can change the motion of objects. As they move through school they should start to identify specific collisions, interactions, and conversions of energy.
Web Resources: Rube Goldberg Machines - Wikipedia

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Description: Rube Goldberg machines are named after American cartoonist Rube Goldberg who drew complicated steps involved in doing a fairly simple task (like pouring milk in a glass). Students can study these machines, or build their own, to show how energy can be converted throu

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Phenomena anchor video- supervolcano

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This resource provides opportunities for students to observe patterns and build understanding about the relationships between volcanoes, earthquakes, and mountain range locations.

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Earthquakes and Volcanoes Interactive | PBS LearningMedia

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Explore the patterns and relationships among the locations of tectonic plate boundaries, mountain ranges, volcanoes, and earthquakes on the planet. Use this resource to visualize data and provide opportunities to develop and use models.

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Advantages and Disadvantages of renewable energy

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Advantages and Disadvantages of renewable energy

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Solar and wind energy videos

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Every creature that's ever lived, including you, has been honed by the powerful force of evolution. Play NOVA's Evolution Lab to learn how it's responsible for the explosion of Earth's biodiversity.

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Studens will need to weigh the pros and cons of each energy source, assess the availability in that area, and consider the needs of the location.

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The world’s energy
consumption is predicted to grow by 56% in the next 25 years*. As the demand
for energy swells, the stores of fossil fuels we currently depend on are
dwindling and becoming more costly to obtain. The burning of these fossil fuels
also discharges carbon, which has long-lasting nega…

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Notice the location of volcanoes on this map and observe the physical features of volcanoes in this gallery of images from NASA

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Band of Volcanoes in the Pacific | PBS LearningMedia

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Notice the location of volcanoes on this map and observe the physical features of volcanoes in this gallery of images from NASA and the National Oceanic and Atmospheric Administration (NOAA). Volcanic eruptions on land and underwater shape and continue to reshape the surface of our planet.

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Global Earthquakes and Volcanoes Map | PBS LearningMedia

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Observe and analyze the locations of earthquakes and volcanoes across the globe with this interactive map that contains data layers for each phenomenon. This resource provides opportunities for students to look for patterns in the locations and prevalence of each phenomenon individually and in relation to each other.

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Graphic organizer to help students organize information about how renewable and nonrenewable resources affect the environment

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Renewable and Non-Renewable Energy Graphic Organizer (Teacher Version) — The Wonder of Science

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The Wonder of Science website aggregates the work of Paul Andersen around the NGSS (Next Generation Science Standards)

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What makes sounds louder?

What is a sound wave?

What is amplitude?

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Sound is a type of energy made by vibrations. When an object vibrates, it causes tiny air particles to move.

Imagine you are sitting in a quiet room with a friend. If you clap your hands, the shock causes the air around your hands to begin vibrating.

When air particles vibrate, they bump into other particles near them. Then these particles begin to vibrate and bump into even more air particles. When the air particles begin vibrating the air inside your ear, you hear a sound.

This chain continues until the particles run out of energy. This is what we call a "sound wave."

So what happens when you turn the up on your stereo or television? Well, you're not only turning up the , you're actually turning up the !

is the of a sound wave. It is directly related to , which is the height of a sound wave.

Imagine a drawing of ocean waves. The highest part of the wave is the crest. The dips in-between each wave are called "troughs."

The distance from the highest part of the crest to the lowest part of the trough is . Sound waves and ocean waves may be made of different things, but they work the same way. Changing the of a sound wave changes its loudness or .

If you are playing a guitar, the vibrations of the strings force nearby air molecules to compress and expand. The of your guitar playing depends on how hard or softly you the strings.

When you a string gently, the sound will be softer because you have transferred less energy to the string. By using less energy, the string does not vibrate as much and will move less air than if you had plucked the same string forcefully .

On the other hand, if you the same string with a lot of force, the note will be much louder. When you use more force to the string, you are using more energy.

This extra energy causes the string to vibrate more, which helps it move more air particles for a longer time. A string plucked with force has greater , and greater makes the sound louder when it reaches your ear.

depends on . Greater produces louder sounds. Look at the following pairs and decide which item has greater :

yell or whisper

siren or cat meow

mosquito buzz or car alarm

fireworks or violin

Colorado University recently studied a small group of iPod users. The researchers found that some of the young people had their music cranked up loud enough to cause long-term hearing damage and didn't even realize it.

Many young people assume the maximum on an iPod is safe, but in some instances, listening to an MP3 player at maximum is just as loud as a chainsaw or rock concert. Over time, loud noises can damage fragile hair cells in the inner ear.

These hairs are responsible for receiving sound waves and sending sound information to the brain. Over time, repeated exposure to loud sounds, including music, can permanently damage these delicate hair cells and lead to permanent hearing loss.

Lowering the and limiting the amount of time spent listening to music on headphones is the best way to protect your hearing.

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Sound is a type of energy made by vibrations. When an object vibrates, it causes tiny air particles to move. Imagine you are sitting in a quiet room with a friend. If you clap your hands, the shock causes the air around your hands to begin vibrating.