Immune System
Immune System is your body's built-in defense team that finds and fights germs to keep you healthy.
Think of it this way
Small dark dots float in a pot of water on the counter — those are germs. Larger white dots drift through the same water as white blood cells. When a white dot meets a dark dot, it wraps around the germ and sinks it. Clean water stays on top, just like healthy blood after your body traps invaders.
Explaining immune system by grade level
When a germ like a cold virus gets inside you, your body goes to work. Special cells in your blood hunt for the germ. They learn what the germ looks like so they can find it fast. Next time that same germ shows up, your body stops it even quicker.