ATP
ATP is the tiny fuel packet that cells burn to power every move your body makes.
Think of it this way
A charged battery holds energy until you need it. ATP is the same — a tiny packet the cell picks up and uses right away. Your cell grabs an ATP packet and snaps it open to release the power stored inside. Once the packet is empty, the cell refills it and uses it again.
Explaining atp by grade level
A firefly lights up at night. That glow takes energy. Inside the firefly, small fuel bits called ATP break open. Each one gives off a burst of power. That power makes the light you see in the dark.