www.bbc.co.uk/news/uk-scotland-glasgow-west-53804140
So it looks like 14 school aged teenagers (it's not clear if they are all school aged, but it sounds like at least 8 are) have contracted coronavirus through being at a house party.
It seems pretty obvious to me that older school kids can both contract and transmit Covid. This does not sound at all like adults passing the virus to kids, this sounds like a super spreading event caused by lots of teenagers indoors in close proximity.