Here's a breakdown of what makes a scientific theory:

* General: It applies to a broad range of phenomena, not just a single observation.

* Principles: It's a set of fundamental ideas that explain how things work.

* Supported by evidence: It's not just a guess; it's backed up by many observations, experiments, and data.

* Explains some aspect of nature: It aims to understand a particular aspect of the natural world, like gravity, evolution, or plate tectonics.

Important to note: Scientific theories are not just "educated guesses." They are rigorously tested and constantly refined as new evidence comes to light. They are also falsifiable, meaning they can be disproven if new evidence contradicts them.

Here are some examples of scientific theories:

* Theory of Gravity: Explains the force that attracts objects with mass towards each other.

* Theory of Evolution by Natural Selection: Explains how life on Earth has changed and diversified over millions of years.

* Cell Theory: Explains that all living things are made up of cells.

* Theory of Plate Tectonics: Explains the movement of Earth's crust and the formation of continents and mountains.

Remember: Scientific theories are powerful tools for understanding the world around us. They are not set in stone, but they are the best explanations we have based on current evidence.