Plate Tectonics
Plate Tectonics is the slow movement of large pieces of Earth's surface.
Think of it this way
A pot of thick soup sits on a low burner. Chunks of bread float on top and drift apart as the soup moves below. Sometimes two chunks collide and one rides up over the other. The slow heat below drives all the motion.
Explaining plate tectonics by grade level
The ground under your feet is part of a big piece of rock. Earth has many big pieces like this. They float on hot soft rock deep below. These pieces move very slowly. They can bump into each other. When they push together, mountains can form. When they pull apart, hot rock rises up. This movement is so slow you cannot feel it.