For as long as there have been archeologists there has been debate about how fire was first created, however watching Charlotte rubbing and banging things together it all seems pretty obvious to me.
Currently she really just starting to get highly mobile and highly curious, and her scientific repertoire of investigative methods currently contains:
1. Lick it or chew on it
2. Shake it vigorously
3. Drop it
4. Rub it againt something else, or try and smack it and something else together.
This last one provides me with amusing parallels to the scientific process in the game evil genius, where your science minions wander around trying to find things that they can combine to make a new thing out of. Although the depicted process is slightly more involved, it still in essence boils down to smack two things together (and shoot them with your giant laser) and see if they make something new.
So I can completely understand how kids could have rubbed two things together and discovered fire, in every aspect apart from their 7 second attention span…