At what age did you let your kid try soldering?

I started my son at 9 with one of those cheap practice boards from the electronics kit aisle, the kind with a row of copper pads you solder random resistors onto. Honestly it was more for me than for him, beacuse watching him on the practice board told me wether his hands were steady enough before we touched anything that mattered. He burned himself once on the iron's metal stand, not the tip, and that little lesson did more for his respect of the tool than anything I could have said. What actually worked for us was keeping the first real job tiny. He soldered two wires to a switch for a flashlight he'd already built, nothing else. Small win, done in ten minutes, huge confidence boost. Then we spaced the bigger stuff out over months instead of doing it all in one sitting. One thing I'd do differently is buy iron with adjustable temprature and set it low to start. My old fixed-temperature one from the 90s ran hot and made learning harder than it needed to be. Also get her her own safety glasses and her own side cutters. Kids take the work more seriously when they have thier own tools on the bench instead of borrowed ones.

If she's careful with a hot glue gun, she's most of the way there already.

I went the opposite direction with my two, and I'd defend that choice. We didn't touch an iron until my younger one was about 11, and by then she'd already built half a dozen things using a breadboard and those little jumper wires. She made a light-activated nightlight and a two-tone doorbell that way, all without a drop of solder. The breadboard meant she coud mess up a connection, pull the wire, and try again in ten seconds instead of waiting for me to fix a cold joint with a hot iron in her hand. The thing I noticed is that at 8 the exciting part is seeing the circuit work, not the joining method. My oldest got bored of twisting wires together and started asking to solder on her own, and that's when I knew she was actually ready, because she wanted the result badly enough to be careful. The younger one didn't ask until two years later and picked it up in an afternoon.

So my honest suggestion is let her build the next two or three projects solder-free. Breadboard, screw terminals, even those lever connectors people use for light fixtures. If she's still bugging you about real soldering after that, get a small pencil iron and a scrap of perfboard and sit closer than you think you need to.

Honestly, I spent years assembling these things before I touched a soldering iron. Most of the early stuff shouldn't require a heat source at all. You need to learn how the electricity moves through the circuit first. Get her comfortable making connections with terminal blocks and wire crimping tools, which are way more sturdy than just twisting two copper strands together. That way, she learns the fundamentals of current flow and proper gauge wiring without the rush or mess of melted plastic. If the basic assembly and logic of the circuit are sound, then the soldering part just becomes a finer skill, not the whole job. Start with the mechanical side first.

I really agree with the point about learning connection types before even thinking about solder. Once you get comfortable making a solid physical link between two wires, the soldering itself becomes just one of many ways to do it. When I was teaching my niece, I started with crimp connectors on small gauge wire. It allowed her to see how diferent terminals fit together and achieved a permanent link without needing a heat source.