At present I am teaching multiple people of all ages nearly every day - at Castell Henlys and at Top of the Woods campsite - and have only had a few that needed me to "guide their hands" (ie hold their hands and do the strikes for them) mainly young children with poor manual dexterity.
Having said that, this summer I have had 3 five-year-olds succeed without help.
All used the charcloth on top of the flint method, though I also demonstrate the "down strike" method. I even reverse grip and down strike to shower my arm with sparks to show they do not hurt!
I do not get paid at Castell Henlys but get through masses of flint and char cloth, not to mention hay for tinder bundles!
The look on folks faces when they make fire is worth it!
Surface area. The tinder needs to be fine enough so ignition of the smallest strands is nearly instantaneous.
Best here is a handful of spruce twigs off the main tree trunk to be driest.
Then bash the bejeezlies out of them between 2 rocks to get XXX fine wood fiber and pitch resin.
Can't ever count on grass being dry here if you can find enough.
Hah!! Finally figured out how to get amadou to take a spark the easy way!!
Just char it and it's as easy as charcloth. In fact, I used the first bit, thought it hadn't taken a spark and put it back into the tin just to find that it was nearly gone by the time I succeeded with the second bit. It was quite windy at the time.
Now I need to go and find more horse hoof fungus
I really struggled to find King Alfred's Cakes (I'm in Farnborough, Hampshire) and there just don't seem to be many Ash trees now, let alone fallen branches However, on a recent trip to the New Forest, I (literally) stumbled upon a fallen branch from an Ash which had a good number of them, so I liberated a couple to try with.
Apparently Ash used to be the third most common tree in England, but I can only guess that Ash Dieback has had a much bigger impact than I (and I suspect many others) appreciated.