TheMetal1: "Also, I agree... kids DO NOT TRY THIS AT HOME... or anywhere."

important point - don't want kids to hurt themselves or start a fire!

to make a magnifier safe for kids, all one has to instruct them that they can play with the magnifier ONLY/STRICTLY IN THE SHADE ("don't let the sun see you...."), where it is basically harmless and safe.

i've had good experiences demonstrating the power of a magnifying glass in the sun. i obviously don't teach kids about solar vaping. instead they get a lesson in energy, physics, optics, geometry and FIRE SAFETY, and they'll learn all the fun kids' stuff that one can do with a magnifying glass, they get look at objects far and near through the magnifier.

under close grown-up supervision, kids may/can be allowed to do solar engraving on wood (never plastic). for kids i recommend small magnifying glasses - about 1inch. smaller magnifying glasses burn less hot and significantly slower.

imho, giving kids as much knowledge as they can handle is far better than just saying "no!" to them. it only results in arousing the kids' curiosity, but deprives them of knowledge and understanding.

this may be somewhat off topic - but it is an important point.