They do it for big football games or Presidential rallies, they do it in crowded federal buildings which are packed to the gills will over-compensated, do-nothing Federal bureaucrats.
And they already have metal detectors and guards in large numbers of schools in US ghettos with a history of gang violence.
Of course its doable.
Further, schools could do a lot more of their educating on-line instead of in-person. No reason why students need to attend 5 days a week, a reduction in the number of days personal appearance is required by 80% would reduce costs
Oh Jesus DO get real. I attend most Boise State football games. It's not a comparatively large college stadium at about 36,000 max capacity. They have minimally 50 entrances and a few hundred security people. Still takes an hour to get everyone in.
I did jury duty last year and the first morning when they opened a single security entrance there were 150 people in line. It took almost half an hour to get that number of people through a single entry point.
Online schools for all? Great - a new generation with zero social skills.