I've been giving and having my sons use knives since late single digits. They keep graduating up the line and I'll be handing out some half-decent fixed blades this year (birthdays) for backwoods use. 
I tend to agree with the philosophy that (a) knives are tools that need to be respected and, thus, a user should develop healthy caution as soon as possible and (b) this can start earlier then many suspect.
A great deal of this will come down to how well you know your kids. Are they mature and responsible enough to carry/use a small knife (I'd say a smallish SAK would be ideal) with out harming themselves (or others for that matter). If so, get them something that will limit damage, teach diligently and they'll get it soon if not later.
FWIW, I've heard before (can't quite remember where) that the Sami and Laplanders traditionally have their kids using razor sharp knives at ages that would invoke Federal legislation here in the states ...
Cheers and good luck.
	
		
			
		
		
	
				
			I tend to agree with the philosophy that (a) knives are tools that need to be respected and, thus, a user should develop healthy caution as soon as possible and (b) this can start earlier then many suspect.
A great deal of this will come down to how well you know your kids. Are they mature and responsible enough to carry/use a small knife (I'd say a smallish SAK would be ideal) with out harming themselves (or others for that matter). If so, get them something that will limit damage, teach diligently and they'll get it soon if not later.
FWIW, I've heard before (can't quite remember where) that the Sami and Laplanders traditionally have their kids using razor sharp knives at ages that would invoke Federal legislation here in the states ...
Cheers and good luck.