Simple version
Tides are mainly caused by the Moon's gravity pulling on Earth's oceans. The Sun also affects tides, but the Moon has the stronger tidal effect because it is much closer.
As Earth rotates, places move through ocean bulges, creating high and low tides.
Why two high tides
There is a bulge of water on the side of Earth facing the Moon, where the Moon's gravity pulls more strongly.
There is also a bulge on the opposite side. This happens because Earth and Moon move around a shared centre of mass, and the far side is affected differently.
Why tides matter
Tides affect coastlines, animals, navigation, fishing, safety and ecosystems. Some life cycles are timed around tides.
Tides also show that gravity is not just something that keeps us on the ground. It shapes oceans.
Common mistake
The Moon does not only pull one side of the ocean up. The Earth Moon system creates two main tidal bulges, which is why many coastlines get two high tides each day.
Try it
Look up a tide table for a UK coastal town and compare high tide times across a week. You will see the rhythm shift each day.
What learners should notice
Tides are space affecting the sea. The Moon's gravity produces a daily rhythm that shapes coastlines and life.
This makes the Moon feel close and practical, not just astronomical.
Build the understanding
Start with gravity, then tidal bulges, then Earth's rotation through those bulges. Add the Sun afterwards for spring and neap tides.
Avoid overloading learners at the start. Build the picture step by step.
AwareSTEM activity idea
Look up tide times for one UK beach across several days. Ask learners what pattern they notice and why the times shift.
Quick recap
How Tides Work sits inside the The Moon part of The Story of Everything. The main point is this: gravity, bulges, and why there are two tides a day not one.
By the end of this page, the learner should be able to explain the idea in plain English, connect it back to the timeline, and say why it matters beyond a school-style fact.
Key words to know
Use these as anchor words while learning this topic: How Tides Work, The Moon, evidence, time, change, system, signal, scale and connection.
The aim is not to memorise every word. The aim is to build a small vocabulary that helps the learner explain the idea clearly to someone else.
Question to ask
Ask: what does how tides work change in the bigger story?
A good answer should not stop at one fact. It should explain what came before, what changed, and how that change affected the next part of the timeline.