Children are messy by nature, and the typical child adult ratio in an Orthodox Jewish crowd, particularly at events you describe, is likely much higher than other groups visiting the establishment. That’s one possible reason. Another reason: Packaged food brought in from the outside tends to generate much more garbage than food bought on premises, so even if the in-the-can vs. on-the-floor garbage ratio is the same between Jewish and non-Jewish crowds, the sheer volume of waste may just be higher. Perhaps these factors could explain why the “entertainment center” became messier than usual during the chol hamoed event. That said, cleanliness is stressed by the Torah, and parents must teach their children to be conscientious and to clean up after themselves.
Menu