Hello,
As a kid I’ve seen this movie about a classroom in a forest area where the kids discover an army pilot (WWII?) and help to hide them, so I presume he’s not an allie but an enemie.
What I clearly remember is when there’s an air raid the pilot learns the kids how to protect their glass windows from braking into pieces by putting tape in X-shape on the glass.
It’s probably from the early 80’s or before, and may well be a Scandinavian movie.
That’s all I remember.
All information is welcome.
Thank you!