You're absolutely right! The movement of tectonic plates does indeed cause changes in the number and shape of continents over incredibly long periods. However, the changes we're talking about are measured in millions of years.

Here's why:

* Plate Tectonics: Earth's outer layer is made up of massive plates that are constantly moving. They collide, separate, and slide past each other.

* Continental Drift: This movement causes continents to drift apart, collide, and even merge into supercontinents. The process of forming and breaking apart continents is incredibly slow.

* Time Scale: While we see dramatic changes in the landscape over geological time, these changes are not noticeable within a human lifetime.

Examples of Continental Changes:

* Pangea: About 300 million years ago, all continents were joined in a single supercontinent called Pangea.

* Continents Today: Over millions of years, Pangea broke apart, forming the continents we know today.

In short, while the movement of tectonic plates is a constant process, it takes millions of years to create significant changes in the number and shape of continents.