Source please?The majority of infections happen when people spend a prolonged time period within 1m of someone who is infectious. For most people that is most likely to happen within a family / friends home, but is also common in workplaces like factories, where social distancing is challenging.
School age kids are the group least likely to pass it on via community transmission in any setting. There's some evidence to suggest that the number of coughs/colds that kids typically have means their immune system is better prepared to fight the virus.
Universities have a major problem, but the cause is the same - people spending prolonged time periods within 1m of each other.
Everything I've read suggests that viral load in school age children doesn't differ significantly from any other age group. Therefore transmission is just by them is just as likely as anyone else. It's just that kids tend only to have mild or no symptoms, except in rare cases. That does mean that they tend to cough less but otherwise they are just as infectious.
If you've seen something different I really want to read it.