Here's a simple, fun, useful, educational activity that (bonus!) kept the girls intensely engaged for nearly an entire morning recently:
I did require the girls to close the matchbox before lighting a match on it, and to keep the matchbox that they were using separate from the other matchboxes that we have, and to stay in one specific area where I knew where they were and that there wasn't anything particularly flammable nearby.
However, I let them practice until they could light a match nearly on the first try, and I let them experiment with lighting more than one match at the same time, and with lighting a match held by a sister with an already burning match, and with how long they could hold their lit match, and with whether they wanted to shake it or blow it out, and I let them panic and drop lit matches onto the ground, and burn their fingers a bit, and they went through at least four entire boxes of matches, and had themselves a wonderful time.
I did the same exact thing when I was their age, only I was hiding in the backyard with my grandmother's stolen cigarette lighter...good times, that.