GET THE SCOPE!!!! Yes, a kid should learn to shoot open sights. That's what an inexpensive .22 target rifle is for, learning how to hit paper or coke cans. But take a young kid, his first hunt, low light, buck fever etc..... He needs all the help he can get Seriously, if he botches the job and its a bloody awful, hours long mess, you could sour him on hunting forever. At the least he'd feel bad. Thats not how any one's first hunt should go. Make it as easy for him as possible to do it right. Plus always teach the virtues of NOT pulling the trigger. Make sure he knows there's always tommorrow if things just don' feel right. I've been doing this for 28 years and I still always prefer a scope over iron with a rifle for deer, if the oportunity presents itself. Just my .04.
FQ13
PS it doesn't need to be a great scope, a Simmons or Bushnell will do just fine at .243 ranges, either 3xby9x or just fixed 4x.