I am teaching two young boys (elementary school) some basics about chemistry, but I have to learn as I go myself.
Is this a viable model to explain oxidation and fire? When we light up the fireplace, oxygen "steals" electrons from the wood, which is carbon. But carbon won't let oxygen just leave with its electron(s), so this theft results in them clinging together, and we call that Co2.
At the moment they cling together, their tight grip gives off heat. We call this an exothermic reaction. This word may not be easy to remember, but think of "exhaust pipe" (going out, so "exo") and "thermos" (it stores something hot). So when you hear exothermic reaction you know it's a reaction that gives off heat.
And how much energy is required to get oxygen and carbon to let go of their tight grip? Exactly the same amout of thermic energy they gave off when they first clung together!