Understanding Day and Night Cycle 1

A student notices that at 8:00 AM, the shadow of a flagpole points toward the west. By noon, the shadow is very short and points slightly northward. By 4:00 PM, the shadow points toward the east. Using your knowledge of Earth's rotation, explain which direction Earth is rotating and how this causes the shadow to move from west to east throughout the day.

• Earth rotates from east to west, causing the Sun to appear to move from west to east, which makes shadows shift from east to west.

• Earth rotates from west to east, causing the Sun to appear to move from east to west, which makes shadows shift from west to east.

• Earth rotates from north to south, causing the Sun to appear to move across the sky, which makes shadows shift randomly throughout the day.

• Earth rotates from east to west, causing the Sun to appear to move from east to west, which makes shadows shift from west to east.

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NGSS.MS-ESS1-1

A student in Texas sets up a vertical stick in an open field and records the length and direction of its shadow every two hours from 6:00 AM to 6:00 PM. She notices the shadow is longest in the morning and evening and shortest at noon. Using reasoning about Earth's rotation, which explanation best accounts for why the shadow is shortest at noon?

• At noon, the Sun is closest to Earth, so its rays are stronger and eliminate the shadow almost completely.

• At noon, Earth's rotation has brought the student's location to a point where the Sun appears highest in the sky, making sunlight strike the stick most directly and producing the shortest shadow.

• At noon, the stick absorbs more heat and shrinks slightly, making the shadow appear shorter.

• At noon, Earth temporarily stops rotating, causing the Sun to stay directly overhead and shorten the shadow.

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NGSS.MS-ESS1-1

Two students are debating why we have day and night. Student A says it is because the Sun moves around Earth once every 24 hours. Student B says it is because Earth rotates on its axis once every 24 hours. Using evidence about shadow patterns and the apparent movement of the Sun, which student is correct and why?

• Student A is correct because the Sun visibly moves across the sky each day, proving it orbits Earth every 24 hours.

• Both students are correct because the Sun and Earth move around each other simultaneously, each completing a half rotation every 12 hours.

• Student B is correct because Earth's rotation on its axis every 24 hours causes different parts of Earth to face the Sun, creating day and night, and also makes the Sun appear to move across the sky, causing shadow changes.

• Student B is correct, but only because the Sun is too large to move, not because Earth's rotation causes day and night.

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NGSS.MS-ESS1-1

A student places a sundial outside at sunrise and observes that the shadow falls on the "6 AM" mark. She plans to check it again at 3:00 PM. Using your understanding of Earth's rotation and shadow movement, predict where the shadow will be and explain the reasoning behind your prediction.

• The shadow will be on the "3 PM" mark because Earth has rotated enough to make the Sun appear lower and farther west in the sky, shifting the shadow to the east.

• The shadow will still be near the "6 AM" mark because shadows do not move significantly during the day.

• The shadow will be on the "12 PM" mark because the Sun always appears directly overhead by the afternoon.

• The shadow will be on the "3 PM" mark because the Sun has physically moved westward across the sky, dragging the shadow with it.

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NGSS.MS-ESS1-1

A student is trying to figure out what time of day it is based only on the shadow of a tree. The shadow is very long and pointing toward the west. Using your knowledge of Earth's rotation and the day/night cycle, what can the student reasonably conclude about the time of day, and what is the reasoning?

• It is midday because the Sun is directly overhead, creating a long shadow pointing west.

• It is early morning because Earth's rotation has just brought the student's location into sunlight, with the Sun appearing low in the eastern sky, casting a long shadow toward the west.

• It is late afternoon because the Sun is low in the eastern sky, casting a long shadow toward the west.

• It is nighttime because long shadows only occur when there is very little sunlight.

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NGSS.MS-ESS1-1

A student observes that during the day, the Sun appears to travel in an arc across the sky from east to west. Her friend claims this means the Sun is orbiting Earth. The student disagrees and says it is Earth's rotation that creates this appearance. What evidence from shadow observations could the student use to support her argument that Earth is rotating rather than the Sun orbiting Earth?

• The student could point out that shadows disappear at night, proving the Sun moves away from Earth.

• The student could argue that since the Sun looks the same size all day, it cannot be moving around Earth.

• The student could show that shadows are always longest at noon, proving the Sun stays in one place while Earth moves.

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NGSS.MS-PS2-4

A student living in Texas notices that when it is daytime where she lives, her pen pal in China is experiencing nighttime. Using your understanding of Earth's rotation on its axis and the day/night cycle, explain why this occurs and predict what will happen to both locations approximately 12 hours later.

• It occurs because the Sun shines on only one side of Earth at a time; 12 hours later, Earth will have rotated halfway, so Texas will be in nighttime and China will be in daytime.

• It occurs because Earth is tilted, causing one side to always be in darkness; 12 hours later, both locations will experience twilight at the same time.

• It occurs because China is farther from the Sun than Texas; 12 hours later, both locations will experience daytime simultaneously.

• It occurs because the Sun moves to shine on different continents; 12 hours later, the Sun will return to shine on Texas again while China remains in darkness.

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NGSS.MS-ESS1-1

A student sets up an experiment where she marks the position of a shadow cast by a fence post every hour for 8 hours. She notices the shadow moves in a consistent, predictable arc. She then creates a model using a flashlight and a globe to replicate this observation. Which manipulation of the globe would best replicate the shadow movement she observed outside, and why?

• Moving the flashlight slowly around the stationary globe from east to west, because this replicates the Sun orbiting Earth and causing shadows to shift.

• Rotating the globe from west to east while keeping the flashlight stationary, because this replicates Earth's rotation on its axis, which causes the Sun to appear to move and shadows to shift in a predictable arc.

• Tilting the globe at different angles while keeping the flashlight stationary, because the tilt of Earth causes shadows to move throughout the day.

• Moving both the flashlight and the globe simultaneously in opposite directions, because both Earth and the Sun move to create the day/night cycle.

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NGSS.MS-ESS1-1

A student is designing a plan to use only shadow observations to determine the time of day without using a clock. She plans to measure the length and direction of a shadow at different times. Using your understanding of Earth's rotation and its effects on shadow position, evaluate her plan and identify what specific shadow data she would need to collect to make her time estimates most accurate.

• Her plan will not work because shadows change randomly and cannot be used to determine time; she should use a thermometer instead to measure temperature changes throughout the day.

• Her plan will work if she collects data on shadow direction only, since the length of a shadow does not change throughout the day and provides no useful information about time.

• Her plan will work best if she records both the direction and length of the shadow at regular intervals, since Earth's consistent rotation rate causes shadows to move from west to east in a predictable arc and become shortest at solar noon, allowing her to estimate time based on shadow position and length together.

• Her plan will work only if she measures shadows at exactly sunrise and sunset, since shadows are only reliable indicators of time at those two moments when Earth's rotation brings the Sun to the horizon.

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NGSS.MS-ESS1-1

What are the reasons for the seasons?

• Earth's tilt and rotation.
• Earth's rotation and revolution.
• Earth's tilt and revolution.
• Earth's tilt and resolution

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NGSS.MS-ESS1-1