All signs belong to the American kind. I find no influence from The Netherlands. Note also that none of the children signs show gender signals. The pedestrian signs to the contrary make a clear distinction even while they are going match-stick.

We must not be blind for what we have seen on several other signs on this site. Road signs often give away what can't be said in the open (Iran, Nepal, Monsieur Jean). In this case that would mean a military undercurrent. But there is also the more comforting possibility of teachers keeping a tight hand on their pupils.