Here's why:

* Temperature and Kinetic Energy: Temperature is a measure of the average kinetic energy of the molecules in a substance. Kinetic energy is the energy of motion.

* Higher Temperature, More Movement: When you increase the temperature of a substance, you're essentially giving the molecules more energy. This extra energy translates into faster movement, vibrations, and rotations of the molecules.

* Lower Temperature, Less Movement: Conversely, at lower temperatures, the molecules have less energy and therefore move slower.

Think of it this way: Imagine a room full of people. If the room is cold (low temperature), people will be sitting or moving slowly. If the room is hot (high temperature), people will be moving around more energetically. The same principle applies to molecules.