1. TAKS objective 5 Earth and Space Systems
Middle School Science
Science TAKS Need to Know
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2. Changes in the Earth over time
Weathering- the process of rocks being broken down into smaller pieces.
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3. Two types of Weathering
Mechanical
Rocks break into smaller pieces by physical means –
Water, ice, wind, gravity, organisms & changing temperatures
Chemical
Rocks break into smaller pieces by chemical reactions – Air, water, acid & salts react with minerals in rocks to form new substances
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4. Erosion
Destructive
The movement of particles from one location to another is erosion
Weathered particles of rock are transported by gravity, living organisms, water, glaciers & wind.
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5. Deposition
Constructive
The settling (depositing) of eroded particles as sediments wherever they are transported by wind or water.
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6. Rock Cycle
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7. Sedimentary
Igneous
Metamorphic
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8. Plate Tectonics
Plate tectonics explains the movement of large sections of Earth’s crust called tectonic plates. The force behind tectonic plate movement is thought to be currents of magma flowing in Earth’s mantle.
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9. Plate boundaries
Tectonic plates slowly collide against one another along plate boundaries. Sections of the plates may break off and be pushed down, up, or to the side. Mountain ranges, ocean trenches, earthquakes & volcanic activity are all common along plate boundaries.
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Pacific Plate is the largest

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San Andreas fault

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13. All the land that drains into a specific body of water.
Groundwater and surface water both contribute to the water in a watershed.
Surface water becomes groundwater by soaking into the sand and soil or by traveling through cracks in rock.
The Watershed game interactive on line
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15. Two important ways that oceans affect climate on land
Land heats up faster than water because land has a lower specific heat than water does. This causes the air over land to heat faster than the air over water. The warm air rises, starting a convection current that pulls air toward land from the ocean. This keeps air over the land from getting too hot and brings moist ocean air inland.
Warm air holds more water vapor than cold air does. When warm, moist air is cooled, clouds form and can produce precipitation. This warm air can be cooled by rising into the colder upper atmosphere, by moving over cold ocean or lakes, or by mixing with colder air. (Ex. Front boundary- the edge where cool, dry air meets warm, moist air. Often causes stormy weather)
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16. Nitrogen Cycle
Nitrogen changes back & forth from nitrogen gas to the nitrogen compounds used by plants & animals.
Nitrogen is passed from plants to other organisms through food webs in the ecosystem. Once plants & animals use the nitrogen it returns to the atmosphere as a gas, completing the cycle.
Some fertilizers contain nitrogen compounds because plants need nitrogen to grow. Though there is plenty of nitrogen gas in the atmosphere, plants can’t use this form. In nature nitrogen can be changed from a gas to a form that plants can use by lightning or by soil bacteria and fungi in a process called nitrogen fixation.
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17. Problems if too much Nitrogen in environment
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18. Carbon Cycle
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21. Effects of carbon on environment
One of the biggest ways humans affect the carbon cycle is by burning fossil fuels.
Burning fossil fuels transforms carbon into carbon dioxide.
Higher levels of carbon dioxide cause the atmosphere to hold more heat energy. This may be the cause of warmer temperatures measured in recent years on Earth. (Called “The Greenhouse Effect”)
This could affect the climate in many places. The kinds of plants and animals in these climates may change if the warming continues.
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22. Without the carbon and nitrogen cycles, there would be no life on earth!
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23. Catastrophic events affect the earth
Earthquakes
Floods
Meteorite crater
Volcanoes
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24. Ways humans affect the earth
Two common forms of pollution:
Gases released into the atmosphere
Chemicals that are carried by water into a watershed
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25. Humans can cause extinctions
Human can change:
The quality of the air, water & soil we use
Ecosystems by removing plants & animals & by introducing new species, such as invasive plants & pets
Invasive species don’t naturally live in the ecosystem where they are introduced.
Invasive species compete with/or drive out native species (species that live naturally in an ecosystem)
FIRE ANTS- invasive species- accidentally introduced to North America from South America. They have few predators in NA & aggressively attack & kill many kinds of native plants & animals. They have upset the balance of ecosystems in many southern states.
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26. Renewable
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27. Non renewable
Fossil Fuels
Natural Gas
Oil
Coal
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28. Inexhaustible
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29. Eclipses
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30. Solar eclipse
When the moon is aligned so that its shadow falls on Earth’s surface, the sun’s light is blocked from reaching part of the Earth. Called solar eclipse because it’s the sun that is being blocked from our view.
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31. Lunar Eclipse
A lunar eclipse occurs when Earth blocks sunlight from reaching the moon. This puts the moon in Earth’s shadow.
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32. 4 main Phases of the Moon
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33. Moon phase diagram
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35. Moon’s Revolution & Rotation
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36. Have you ever noticed that the sun travels lower across the sky in winter than in summer? This is because Earth is tilted on its axis at a 23.5o angle.
Seasons
During winter part of Earth tilts away from the sun. This causes the sun’s rays to strike that part of Earth at a lower angle than in the summer.
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37. Seasons- Remember it’s the TILT of the Earth that causes the seasons
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38. Winter Solstice- shortest day of the year
Days are shorter & nights are longer during winter. This occurs in December in the Northern Hemisphere & in June in the Southern Hemisphere.
Each hemisphere receives less sunlight & therefore less heat energy during the winter. This is why temperatures are colder during winter.
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39. Summer Solstice- longest day of the year
This occurs in June in the Northern Hemisphere and in December in the Southern Hemisphere.
Earth’s revolution around the sun causes part of the Earth to tilt toward the sun at different times of the year. This causes that part of the Earth to receive more sunlight at a more direct angle. This is why days are longer and nights are shorter.
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40. Equinox Equinox- means “Equal Night”
Daytime lasts exactly as long as nighttime on the first day of autumn – the Autumnal Equinox (about September 21) and the first day of spring - the Vernal Equinox (about March 21).
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41. 8 Planets
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42. The Sun & Gravity
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43. The Sun is a Star Our sun is a medium-size yellow star.
In the sun, hydrogen undergoes nuclear fusion, a process that releases vast amounts of energy. During fusion hydrogen atoms join to form helium atoms.
Hydrogen fusion is the source of light, heat, and other radiation from the sun.
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44. Comets
Comets are made of various solids (like dirt & dust) and ice crystals. When their orbits take them close to the sun, dust and ice heat up to produce a “tail” behind the comet. Larger comets may even become visible without the aid of a telescope.
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45. Asteroids
Asteroids are rocky and usually follow regular orbits around the sun.
Asteroid belt- the area between Mars and Jupiter that contains many asteroids orbiting the sun.
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46. Nebulae
Nebulae are huge clouds of dust and gas. Some scientists think that our solar system was formed from nebula.
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47. Spiral Irregular Elliptical
Galaxies are groups of millions or billions of stars.
The galaxy we live in is the Milky Way galaxy and has over 100 billion stars. It would take 100,000 light years to travel across it!
Irregular
Elliptical
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48. That’s the Speed of Light!
300,000,000 meters per second is the same as 300,000 kilometers per second.
That’s the Speed of Light!
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49. Light Speed!
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50. Closest star to Earth (besides the Sun)
Proxima Centauri is the nearest star to our Solar System.
Traveling at the speed of light, it would take about 4 years & 3 months to reach it from Earth. (That makes it about 280,000 times farther away from Earth than our sun!)
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51. H-R Diagram
In the Hertzsprung-Russell diagram each star is represented by a dot. Stars are plotted by their luminosity (brightness) and surface temperature.
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