Scientists categorize everything in the universe into two categories: matter and energy.  Matter is anything “that’s actually a thing.”  Any solid, any liquid, any gas.  Anything made of atoms.  Energy is NOT ‘things.’  Energy includes heat (thermal energy), the energy of motion (kinetic energy), the energy we learned about that travels through ecosystems (chemical energy), electricity, and others.  Light, primarily, is a form of energy.  Specifically, light is a form of energy that the human eye can see.  Interestingly, light is the ONLY thing you can see.  When you see something, you don’t actually see that thing, you see the light that reflects off of it and into your eye.

Today, we’re going to start learning about light by seeing how it interacts with matter - what happens to it when it “runs into” different things/matter.  There are five possible things that can happen to light when it interacts with matter.  Today we’re going to learn the first 3.