7 th Grade Science State Assessment Review

1. 7th Grade Science State Assessment Review https://sas.elluminate.com/p.jnlp?psid=2014-02-07.0836.M.CE19F434D56E599313E9D05729AAD2.vcr&sid=559

2. Standard 4Earth and Space Science The student will apply process skills to explore and develop an understanding of the structure of the earth system, earth's history, and earth in the solar system.

3. The student will understand that the structure of the earth system is continuously changing due to earth's physical and chemical processes • (S4.B1.1) -- The student identifies properties of the solid earth, the oceans and fresh water, and the atmosphere. • (S4.B1.2) -- The student models earth's cycles, constructive and destructive processes, and weather systems.

4. A Look at the Earth's Layers • Observe any fruit such as an orange, apple, peach, or grape. Now, cut the fruit in half. You will see that the interior of the fruit is quite different from the exterior. Like a fruit, earth is made up of layers.

6. Layers of the Atmosphere Composition of the Atmosphere • What is the atmosphere made of? Gas! There are molecules of over eight different kinds of gases in the atmosphere with nitrogen being the most abundant. Also in the atmosphere are water vapor and small liquid and solid particles. • Observations over time and advances in technology have shown that the atmosphere is made of several distinct layers. The layers are classified by differences in temperature, air pressure, and density.  The lowest layer, extending just seven miles from earth’s surface, contains all of the weather we experience and the air we breathe.

7. Layers of the Atmosphere Differences in Density • There are five layers of the atmosphere. They are defined by their height, or altitude, above earth’s surface. • The bottom layers contain more gas molecules than the top. The layer closest to earth, the troposphere is more dense than any other layer. The very thin air of the exosphere, is the least dense. The exosphere is the last layer of the atmosphere. Gases in the exosphere can escape earth's atmosphere and go into space Air Pressure • Air, even though you cannot see it, is matter and has weight. Gravity pulls it down and it presses on everything underneath it.

9. Temperature • While density and air pressure both decrease with altitude, temperature fluctuates or rises and falls. Activity in the Atmosphere • At any given time of day or night, there is activity in the atmosphere. In the troposphere, where weather occurs, it may be clear skies in one part of the world whereas  in another part, a plane could be navigating through turbulence caused by wind or clouds. • Weather balloons may be recording data in the stratosphere, while above meteorites burn up from friction in the mesosphere. In the thermosphere, charged particles trapped in earth’s magnetosphere produce spectacular aurora, known as the northern lights in the Northern Hemisphere. Satellites or even a space shuttle are in orbit.

10. The Atmosphere’s Protection • In the stratosphere, there is a very important gas called ozone. • Ozone absorbs rays of damaging ultraviolet (UV) light coming from the sun. In large doses, ultraviolet rays can harm skin, causing sunburn, aging, and skin cancer. UV light can also damage eyes.

11. Conduction, Convection, and Radiation Conduction: From the Ground to the Air • Conduction is one way that heat is transferred from the earth’s surface to the air. In nature, heat always moves from a warmer object to a cooler object. If you sit on a cold, metal chair it will gradually warm up with your body heat. • The same thing happens to air. When air molecules touch the warm ground or water on earth’s surface, heat is conducted from the ground or water to the air molecules, heating them up.

12. Convection: Movement of Matter • In earth’s atmosphere, differences in temperature cause movement of air. Why should air move at all? Why doesn’t hot air just stay where it is? The answer has to do with density. Cold air is denser than warm air. If cold air is above warm air, it will sink and force the less dense warm air to rise up. • Convection is a type of heat transfer that only occurs in fluids, such as in liquids or gases. • The warm air rises and takes heat with it. Eventually it cools and sinks. • Convection is the main way that heat moves from one place to another in earth’s troposphere.

13. Radiation from the Sun • Radiation is a kind of heat transfer that does not need any matter between the heat source and the heated object. Radiation can travel through the vacuum of space. • We feel heat from the sun even though we are not touching it. Sunlight, a form of energy, travels through space without the aid of fluids or solids until it hits a surface that absorbs it, such as earth. Some of the energy is absorbed by the earth as heat and some of it is reflected. • The energy radiated to earth from the sun itself is known as electromagnetic radiation and it includes visible light, infrared, ultraviolet, X rays, and even radio waves. • Your eyes can see the visible light portion of the sun’s radiation, and your body can feel the sun’s invisible infrared radiation as heat.

14. What Happens When Radiation Reaches Earth? • It might seem that all the heat we feel when we go outside on a sunny day is coming directly from the sun. Some is, but for the most part, that energy has taken a more complicated route.  • About 28 percent is reflected or scattered by the atmosphere. Gases and clouds in the atmosphere absorb about 24 percent of incoming solar radiation. The rest travels all the way through the atmosphere to the earth’s surface. Some of that radiation is reflected by the earth’s surface, but most is absorbed by it.

15. Radiation from Earth to the Sun • Recall that all of earth’s weather occurs in the troposphere. For the most part, the air in the troposphere is heated from below by the earth’s surface rather than from above by the sun. This is one reason the temperature in the troposphere drops in higher altitudes – it is farther and farther away from the ground

16. The student will understand past and present earth processes and their similarity. • (S4.B2.1) -- The student understands that earth processes observed today (including movement of lithospheric plates and changes in atmospheric conditions) are similar to those that occurred in the past; earth history is also influenced by occasional catastrophes, such as the impact of a comet or asteroid.

17. Plate Tectonics • At earthquake zones, scientists could demonstrate where the ocean crust was being created and old crust was sinking back into earth’s mantle. Scientists concluded that the surface of the planet is divided into a number of moving sections, called tectonic plates. • The theory of plate tectonics explains that earth’s continents move as part of plates in the lithosphere. Scientists have identified about a dozen major tectonic plates as well as some smaller ones. Where these plates interact, there are numerous earthquakes and volcanoes. • Both earthquakes and volcanoes are related to disruption of the earth’s surface. This disruption occurs mostly at the edges of the plates, where they interact with one another. Earth’s plates move against one another in different ways, producing some interesting results.

18. Three Kinds of Plate Motion • Mid-ocean ridges occur at divergent plate boundaries where plates are moving apart and magma is surfacing. At convergent plate boundaries, one plate pushes on the edge of another plate, forming mountains for continental-continental plate collisions and deep-sea trenches for ocean-continental plate subduction. Earthquakes occur at transform plate boundaries. • The motion of plates is due to two forces: gravity and convection in earth’s mantle. Convection is a circular motion in a fluid that occurs because of differences in density. This motion can explain some of the movements of the crust that scientists have observed. • The source of energy for convection in the mantle is the thermal energy (heat) deep inside the earth. This thermal energy causes rocks to melt, makes the mantle flow, and provides much of the energy to move continents.

19. Impact Craters • Some meteorites strike the earth so hard that they explode on impact, producing an impact crater. Impact craters also form on other planets and moons when large meteoroids strike them. • One of the most well-known impact craters on earth is located in Winslow, Arizona. Named after the engineer Daniel Barringer, who identified it as an impact crater, Barringer Crater (also called Meteor Crater) is 1.2 km (0.75 mi) in diameter and 180 m (600 ft) deep. Scientists estimate that the meteorite that created the crater was about 50 m (150 ft) across

20. The student will identify and classify stars, planets, and other solar system components. • (S4.B3.1) -- The student compares and contrasts the characteristics of stars, planets, moons, comets, and asteroids.

21. The Solar System • You know that the sun warms you, providing energy. It is also the center of our solar system. Solar systems consist of groups of objects that orbit a star. We call the star at the center of our solar system the sun. The earth is just one of the objects that orbits the sun in our solar system. Seven other planets, three known dwarf planets, and many asteroids and comets all orbit our sun. Moons, like earth’s own moon, are also part of the solar system. Moons orbit their planets as the planets move around the sun. • Our solar system extends well beyond Neptune, the farthest known planet, to wherever the last piece of material is orbiting our sun. In addition to planets, moons, asteroids, and comets, the solar system includes small rocks, dust, and gas. The only star in our solar system, however, is the sun. The stars you see at night are located in other parts of the galaxy. • To help you memorize the order of planets, you can come up with a mnemonic device. • One example, My Very Earnest Mother Just Served Us Nuts, is a mnemonic device to remember the order of the planets.

22. Asteroids, Comets, and Meteoroids • Between Mars and Jupiter is a large area containing chunks of rocky "almost planets." Where did they come from? Many scientists think that they are leftover pieces from the early days of the solar system that were unable to form a planet. These rock pieces, called asteroids, are irregularly shaped and pocked with craters from collisions with other objects in space. They could also have broken off from a planet or other body after a collision. • Asteroids can be very large. In fact, the largest asteroid, Ceres, is fairly round and was originally classified as a planet. For this reason, asteroids are sometimes called minor planets or planetoids. Some asteroids even have a core like a planet. • Scientists think that asteroids in the asteroid belt were unable to form a planet because of the nearby presence of Jupiter. Why? Jupiter is so massive that it has an enormous gravitational effect on other objects nearby. Scientists think that Jupiter’s gravitational pull prevented the asteroids in the asteroid belt from coming together to form a planet. • Asteroids exist in space in places other than in the asteroid belt. Mars, Jupiter, and Earth all have groups of asteroids near them that orbit the sun. Scientists closely watch the asteroids near Earth. That way, they hope that they can predict any future collision with an asteroid.

23. Comets: Ice, Gas, and Dust • A comet is a small icy object that orbits the sun. It has three basic parts: a nucleus, a coma, and a tail. • Within the nucleus is a core made of ice, rock, and dust. As a comet nears the sun, the coma, a cloud of dust and gas, forms. As the sun’s energy causes ice in the comet’s nucleus to become gas, solar wind pushes the gas from the coma, and the comet gets a bright tail. Most comets are nearly invisible until their orbit brings them closer to the planets. This is because comets don’t glow or produce a coma, or tail, until they approach the sun where sunlight reflects off the gas and dust. • Many comets have separate gas and dust tails. The gas tail always points away from the sun. The dust tail points back along the path the comet travels.

25. Meteoroids and Meteors • The shooting star is actually a meteor. A meteor is the flash of light created by a meteoroid as it passes into earth’s atmosphere, where it vaporizes. • Meteoroids are small pieces of rock or dust in space. Surprisingly, most meteoroids are as small as a grain of sand. Many scientists think that comets leave these tiny meteoroids behind in their dust trails as they orbit the sun. • Meteor showers are brilliant displays during which you can see lots of meteors in the sky in a short period of time. They happen every year about the same time, when the earth’s orbit brings it into contact with the dust trails of passing comets. • If a meteroid makes it to earth’s surface, it is called a meteorite.

26. The student will model motions and identify forces that explain earth phenomena. • (S4.B4.1) -- The student demonstrates and models object/space/time relationships that explain phenomena such as the day, the month, the year, seasons, phases of the moon, eclipses and tides.

27. Earth's Seasons • Because of the earth's spherical shape and its tilted axis of rotation, the angle of sunlight • More solar energy is transferred from the sun to places on earth's surface where the sun's rays are directly overhead, at a 90° angle to earth's surface. • Think about the tropics, where it is generally warm year round. Why? The tropics are near the equator, and the equator faces the sun more directly all year long. As a result, the tropics receive more direct sunlight and have a warmer year-round temperature. • Areas north and south of the equator have climates that are more temperate. That's because the angle of light in these locations causes the sun's energy to be spread out over a larger area, which results in colder weather that reaches the earth varies in a way that helps make our seasons.

28. Earth's Rotation • One rotation of the earth takes about 24 hours, or one day, which is equal to the amount of time between one sunrise and the next. • As earth’s rotation moves you into night, the sun sets, and now you are on the side of the earth facing away from the sun. Since there is no sun shining at night, the temperatures go down. • As the earth revolves around the sun, earth’s tilt causes different areas of earth's surface to be exposed to various intensities of sunlight during different months of the year. • The more directly the sun strikes a place on earth’s surface, the more concentrated the energy is and the warmer it will be. Areas that receive less direct sunlight experience colder months. • The temperature on earth’s surface during different seasons is also affected by the passage of the sun’s rays through the atmosphere. The earth’s atmosphere absorbs some of the sun’s energy before it reaches the surface, and the sun’s rays that hit the earth’s surface less directly must go through more atmosphere before they reach the surface. • If the earth were not tilted, areas would experience the same level of light intensity year-round, and there would be no seasons.

29. Moon Phases How Moon Phases Happen • Here’s how it works: The moon reflects the sun’s light. As the moon revolves, half of the moon faces the sun and so it is lit up by sunlight. When the sun and moon are on opposite sides of the earth, the sun lights up the entire portion of the moon that faces earth and we see the full face of the moon. • When the sun and moon are on the same side as earth, we cannot see the side of the moon lit by the sun. The moon becomes invisible to us—this is called a new moon. • Full moon and new moon are part of eight different moon phases that occur during its revolution around the earth. The side of the moon we see from earth is called the near side. During a full moon, we see all of it. Sometimes, we see half the moon’s near side and other times, we see only a part of it. And there are times when we cannot see any of it. Crescent and Gibbous • Moon phases are named after the shape the moon resembles during that time. For example, gibbous means humpbacked. So, the gibbous moon is a shape that is between a half-circle and full circle. A crescent moon is the shape of a crescent, which looks like the edge of a fingernail.

30. Moon Phases cont. Waxing and Waning • Moon phases are divided into periods during which the moon waxes or wanes. • Waxing means growing in size.  During the waxing period, more and more of the moon becomes visible until eventually we can see a full moon. • Waning means shrinking in size. The moon is waning when the amount of light reflected off the moon’s surface toward earth decreases. Following this period is an invisible, new moon • The moon waxes for the first half of its revolution. Above, find the photos of the waxing crescent and waxing gibbous moons and look at the image of the earth above them. The moon has made less than half of its revolution around the earth. • First quarter and third quarter phases describe when half of the moon on the near side is lit by sunlight. They are called quarters because we see one-quarter of the moon. A full moon occurs when the whole near side of the moon is lit

32. Eclipses • The word eclipse comes from the Greek word ekleipô, which means to vanish. Eclipses occur when one body passes into the shadow of another body. You can eclipse something by standing in front of it and making it disappear from another person’s view. • In space, eclipses occur when the moon, sun, and earth line up in a certain way. With constant motion of the earth and moon, it’s not surprising that these planetary bodies sometimes line up. • There are two types of eclipses—lunar and solar. The difference between them is related to which body is blocked by another—or how the earth, moon, and sun are aligned.

33. Lunar Eclipse • Use the slider to model a lunar eclipse. When earth is directly between the moon and the sun, the light from the sun is blocked and the earth casts its shadow onto the moon. The moon turns dark. • Two shadows are produced during a lunar eclipse. The inner, darkest, cone-shaped shadow is the umbra. A total eclipse occurs when the moon passes through the earth’s umbra. The outer, larger, lighter shadow is the penumbra. If the moon only passes through earth’s penumbra, a partial lunar eclipse results

34. Solar Eclipse • A solar eclipse occurs when the moon moves between the sun and earth. • The area of earth that is within the umbra experiences a total solar eclipse. The areas of earth that are within the penumbra experience a partial solar eclipse • When the moon covers up the sun, you can see the sun's outer layer called the corona. It makes a fiery ring around the dark spot created by the moon. • Solar eclipses can happen on other planets, too. Whenever two space bodies are aligned with the sun, an eclipse will occur.

36. Ocean Tides What are Tides? • Tides are actually caused by gigantic waves moving through the entire ocean. Their wavelength is half the circumference of the earth. The crest of the wave is high tide and the trough of the wave is low tide. • Just like smaller waves, tides are created by energy running through water. However, in this case, the energy is moving through the entire ocean. • Tides are not caused by wind, like the waves we described in our previous lesson. Tides are caused by gravitational interactions between the earth, sun, and moon.

37. Ocean Tides Cont. How Does Gravity Create Tides? • As the moon orbits the earth, its gravitational pull is greatest on the side of the earth that is closest to the moon. This pulls on the water creating what is called a tidal bulge. • The moon also pulls on the solid earth, which results in a bulge of water on the far side of the earth as well, where the moon’s gravitational pull is the weakest. These bulges are called high tides, and the areas that are not in direct alignment with the moon, midway between the bulges experience low tides.

38. Ocean Tides Cont. High and Low Tides • As the earth rotates throughout the day, different areas experience low tides and high tides • The daily tides occur during a 24-hour, 50-minute cycle. This is a little longer than a day because the moon is orbiting earth while earth rotates. As a result, the tides don’t occur at exactly the same time from day to day How Often Do Tides Occur? • Most areas on earth have two high tides and two low tides each day. In these places, high tides occur approximately every 12 hours and 25 minutes. • However, some places have only one high tide and one low tide each day. There are several reasons why various locations on the earth may experience a different number of low and high tides

39. Ocean Tides Cont. • As the moon orbits earth over the course of a month, the relationship between the moon, earth, and sun changes. This affects the gravitational pull on earth and its oceans, which in turn, affects tides. This changing relationship causes spring tides and neap tides. • A spring tide occurs about twice a month when the moon’s orbit places it in alignment with the earth and the sun at the same time. The combined gravitational pull of the sun and the moon is very strong, creating even larger high tides. So, spring tides have high tides that are higher than normal, and low tides that are at their lowest. • During a neap tide, the moon and the sun are at right angles to the earth. In this case, the gravitational pull of the moon and the sun work against each other making the gravitational pull on the earth’s water weaker. In this position, the high tides are lower than they are normally and just the opposite happens with the usual low tides, which become a bit higher.