Mild pyromania is very natural in a geekchild’s psyche. I’m not talking incinerating ants with a magnifying glass or burning down abandoned buildings. Most kids don’t do Dahmer stuff like that. But lighting matches or playing with Dad’s Zippo is an urge most kids can’t resist.
There is a lot to like about fire. It’s a sensual experience, with flickering light, the warmth of a nearby flame, the smell of a stick turning to char. But there can be consequences. Visualize burn wards filled with sad kids who played with one match too many, or of whole families roasted alive by their ne’er-do-well kids.
Your mission is simple: Satisfy this itch in a safe and educational fashion. Forget playing with matches in the Weber. Let’s talk flamethrowers, Greek fire, gunpowder volcanoes, dry cleaner hot air balloons. Even experiments like "what burns when, and why?" would be a fun and educational start.
What happens when you add copper sulfate to that fire? What happens when you take away the flame’s oxygen supply? Okay kids, let’s ditch the theory and just blow something up.
When it comes to safety, every geekdad will have to decide how paranoid to get. I certainly didn’t take any precautions when I set off the giant heap of black powder in my parents backyard when I was 10 — of course, my parents didn’t know about it. But this is a more enlightened age. Skin, eye and hair protection should be mandatory. Maybe make it fun with lab coats, hard hats, gloves and goggles so they feel like real scientists. This might also be a great opportunity to teach basic (or not-so-basic) fire safety and first aid procedures.
You might also want to consider how much supervision the kids need when doing their fire experiments. Again, every geekchild is different and every geekhouse has different rules.
If you need help finding cool fire experiments, you can’t do much better than William Gurstelle‘s books: Whoosh Boom Splat, Backyard Ballistics, and Adventures from the Technology Underground. Gurstelle, a Minneapolis author and Make contributor, has a knack for all sorts of crazy backyard inventions, not only fire-related gadgets but such fun projects as potato cannons, trebuchets, and rail guns. Get burning!