Discover how the Moon's gravity pulls on Earth's oceans to create tides, and learn why the sea rises and falls every single day.
Learning Goals
By the end of this lesson, you will be able to:
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Explain how the Moon's gravity causes tides on Earth
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Describe the difference between high tide and low tide
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Identify why there are about two high tides each day
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Connect the Moon's position to the ocean's movements
Before You Start
Before this lesson, you should know:
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You should know that the Moon orbits (travels around) the Earth
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You should know that gravity is a force that pulls objects toward each other
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You should know that oceans are huge bodies of water covering much of Earth
A little bit of background will make this lesson much easier to follow.
Key Words
Important words to know for this lesson:
Gravity
An invisible force that pulls objects toward each other. The bigger an object, the stronger its pull.
Tide
The regular rise and fall of the ocean's water level along the shore.
High Tide
When the ocean water rises and reaches its highest point on the beach.
Low Tide
When the ocean water drops and reaches its lowest point, leaving more sand uncovered.
Orbit
The curved path one object takes as it travels around another object in space.
The Moon Pulls the Ocean! 🌙
Tides are the daily rise and fall of the ocean, caused mostly by the pull of the Moon's gravity on Earth's water.
Gravity Reaches Across Space: Even though the Moon is far away, its gravity is strong enough to tug on Earth's oceans and pull the water toward it.
High Tide Bulges: The water gets pulled up into a bulge on the side of Earth facing the Moon. This spot has a high tide.
Two Bulges at Once: Surprisingly, there's also a bulge on the opposite side of Earth, so most places get about two high tides each day.
Earth Keeps Spinning: As Earth spins once every 24 hours, different beaches move in and out of these bulges, so the tide rises and falls.
Example
Imagine spinning a bowl of water while a magnet gently pulls the water to one side. As the bowl turns, each part of the edge takes a turn being high and low — just like beaches during the day!
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The Moon's gravity pulls Earth's ocean water into two bulges, creating high tides on opposite sides of the planet.
Let's Try It Together!
Basic
The Moon takes about 28 days to orbit Earth once. If the Moon is halfway through its orbit, how many days have passed?
Let's Try a Harder One!
Intermediate
Most places on Earth get 2 high tides each day. How many high tides happen in one week?
Your Turn to Practice
Try this one yourself — use the hint if you get stuck:
If there are 2 high tides and 2 low tides each day, how many tides (high and low together) happen in 3 days?
In the Real World
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Beach visitors check tide charts so they don't set up their towels where high tide will soak them later!
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Big ships wait for high tide to enter shallow harbors so they don't scrape the bottom.
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Crabs and clams live in the tide pools that appear when low tide pulls the water back.
Quick Check
Test your understanding — tap an answer to check:
Q1.What mainly causes ocean tides on Earth?
Q2.About how many high tides does most of the coast get each day?
Q3.At low tide, the ocean water...
Challenge Question
Optional
Stretch your brain — this one's a bit harder!
If a high tide happens around 6:00 in the morning, and high tides come about every 12 hours, about what time will the next high tide be?
Key Takeaways
1.The Moon's gravity pulls on Earth's oceans, creating tides. 🌙
2.High tide is when ocean water rises up the beach; low tide is when it pulls back.
3.Most coasts have two high tides and two low tides each day.
4.Tides follow a regular pattern, so people can predict them with tide charts.
Printable Cutouts
Matched to this lesson — untick anything you don't need, then print.
AI matched
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Ready to Practice?
Now that you've learned Earth, Moon & Tides, put it to the test with a quick quiz!