
Larry C. answered 12/21/18
Computer Science and Mathematics professional
As the wording is somewhat ambiguous, it depends on how you interpret 'onward for 28'. Assuming this should be interpreted as 'closed on the 15th and for the following 28 days', 16 of those days would reach the end of December and the remaining 12 days to January 12th. School would then reopen the next day or January 13 if we further assume that MLK Day doesn't enter into it.