The free "Kid's adventure passport" gets NSW primary school children (K-6) into a range of "cultural" attractions for free (including Powerhouse Museum, Australian museum and many more), full list here: http://www.kidspassport.nsw.gov.au/participating-venues , from 1st January until 26th April 2011. You can apparently pick up a "passport" for free at any of the venues, or request one be sent out on the website (I received mine in the mail, took about a week). If you collect stamps at the places (including places which have free entry), you can also go in a draw for some prizes. If you get 3 stamps, you can get an "Adventurer’s Certificate" from the premier (wonder who will be premier then … )
Note that the passport does not include admission for the accompanying adult(s), or older children.
It says K-6, so I doubt it. sorry