The relevant gazette for 2012 is Government Gazette S 393, published on 2 December 2011. It contains a table of the declared school days for the coming year:
School Days Period 1 = 30 January 2012 to 30 March 2012
School Days Period 2 = 16 April 2012 to 29 June 2012
School Days Period 3 = 16 July 2012 to 21 September 2012
School Days Period 4 = 18 October 2012 to 21 December 2012
These days are school days unless there is local signage that says otherwise.
This information has been added to the TABLE menu on the right.