The England Under-19s forward – a European champion with the Young Lions in 2013 – has been in red-hot form for the Sky Blues, scoring eight goals in nine appearances.
England v Macedonia
2pm, Thursday 8 October
Finland v England
2pm, Saturday 10 October
England v Italy
2pm, Tuesday 13 October
Mowbray has been in regular contact with Armstrong’s parent club manager, Steve McClaren, and the two coaches are in agreement over how the 18-year-old’s talent should be nurtured.
Mowbray told CCFC.co.uk: "I had a good long chat with Steve last week. He wants to know how he's doing and he wants to know how we're playing him.
"He's not just stood up front between the two centre-halves, he's developing his game.
“He's a part of the team and the way we function, and we've played him behind the main striker and on the wings which is important for him.”
Armstrong had already made 15 Premier League appearances for Newcastle before he agreed to move to the Ricoh Arena, but Mowbray believes Coventry is an ideal proving ground for young talent, with England U20s pair Bryn Morris and Ryan Kent also enjoying loan spells under his tutelage.
"It's important that if he wants to play in the Premier League that he develops his football knowledge,” said the former Middlesbrough, West Bromwich Albion and Celtic manager.
“With total respect to this league, he won't be sprinting away from Premier League centre-halves like he does at this level.”
He added: "They spent £15 million on a striker in the summer and they've got some great players there who are ahead of him.
"Put it into context really, he's an 18-year old boy who needs to develop his game.
“The qualities he has hurt defenders in this league but at this moment in time, I don't think he'd be able to do that to Premier League defenders.
"He needs to keep doing what he's doing. He listens to game-plans and tries to understand the different roles he can play which will be important for his development.”
Mowbray added: "We've just got to let the boy enjoy his football. He's very respectful of the group and I really enjoy working with him as he is very humble, and just because he's scored a few goals doesn't mean that he wants to stop learning."
Armstrong has joined up with Aidy Boothroyd’s England Under-19s squad, who over the next eight days play hosts Macedonia, Finland and Italy in their bid to progress to the UEFA European Championship 2016 elite qualifying group.