Earth Science: Ocean Tides How the Moon Pulls the Water
Learning how the Moon's gravity affects ocean water
Earth Science: Ocean Tides How the Moon Pulls the Water
Learning how the Moon's gravity affects ocean water
Earth Science - Grade 4-5
- 1
What is a tide?
Think about how the water level at the beach changes during the day.
A tide is the regular rise and fall of ocean water along the shore. - 2
What force from the Moon helps cause ocean tides on Earth?
The Moon's gravity helps cause ocean tides by pulling on Earth's ocean water. - 3
During high tide, is the ocean water level near shore higher or lower than usual? Explain your answer.
The word high gives a clue about the water level.
During high tide, the ocean water level near shore is higher than usual because more water has moved toward that area. - 4
During low tide, many rocks and tide pools can be seen along the shore. Why can these areas be seen more easily at low tide?
These areas can be seen more easily at low tide because the ocean water level is lower and less water covers the shore. - 5
A student says, "The Moon pulls only on land, not on water." Is the student correct? Explain.
Gravity can pull on many kinds of matter.
The student is not correct. The Moon's gravity pulls on Earth, including the ocean water, and this pull helps create tides. - 6
Most ocean places have about two high tides and two low tides each day. If a high tide happens in the morning, what kind of tide will usually happen next?
A low tide will usually happen next because high and low tides happen in a repeating pattern. - 7
Look at this tide schedule: high tide at 6:00 a.m., low tide at 12:00 p.m., high tide at 6:00 p.m., and low tide at 12:00 a.m. How many high tides are listed?
Count only the times labeled high tide.
There are two high tides listed, one at 6:00 a.m. and one at 6:00 p.m. - 8
Why does the side of Earth facing the Moon often have a high tide?
The side of Earth facing the Moon often has a high tide because the Moon's gravity pulls ocean water toward it, making the water bulge outward. - 9
The Sun also has gravity. Why does the Moon have a strong effect on Earth's tides even though the Sun is much bigger?
A nearby object can have a strong pull even if it is smaller.
The Moon has a strong effect on Earth's tides because it is much closer to Earth than the Sun is. - 10
Spring tides happen when the Sun, Earth, and Moon line up. These tides have very high high tides and very low low tides. Which arrangement would make a spring tide: lined up or at a right angle?
A lined up arrangement would make a spring tide because the gravity of the Sun and Moon work together more strongly. - 11
Neap tides happen when the Sun and Moon pull from different directions at about a right angle. Are neap tides usually stronger or weaker than spring tides?
Pulls in different directions do not combine as strongly as pulls in the same direction.
Neap tides are usually weaker than spring tides because the Sun and Moon are not pulling in the same line. - 12
A boat is tied to a dock. In the morning, the boat is floating high beside the dock. Later, the boat is much lower and the muddy bottom is visible. What changed?
The tide changed from high tide to low tide, so the water level dropped and more of the shore became visible. - 13
Draw or describe what the ocean water might look like around Earth when the Moon is pulling on it. Include where a high tide would be.
A bulge means the water sticks out farther than usual.
The drawing or description should show ocean water bulging toward the Moon, with a high tide on the side of Earth facing the Moon. - 14
Why do scientists and sailors use tide charts?
Scientists and sailors use tide charts to predict when high and low tides will happen and to plan safe activities near the ocean. - 15
Complete the explanation: Ocean tides are mainly caused by the Moon's gravity pulling on Earth's oceans. As Earth rotates, different coastlines move through areas of high and low water. What does this cause at the shore?
Use the words high tide and low tide in your answer.
This causes the water level at the shore to rise and fall in a regular pattern of high tides and low tides.