Hi Fordy, and welcome to cruise-chat. We're long-time NCL cruisers and have always been pleased with its Kids Program. Even on ships with very limited dedicated space (and those ships are no longer in the fleet), they did a great job and our son enjoyed it.
You can click here
for information on the Kids Programs and what they offer both kids and families. On Norwegian Sky, the Kids Corner is located forward on International Deck (deck 7), yet they might also meet in other areas of the ship.
You are going at a time of year when there should be plenty of families onboard as most schools are still on summer break.
Happy to answer additional questions.