There are lots of things happening in Melbourne over January during the school holiday period. There are the usual things to see and do for kids that include going to the Aquarium, the Melbourne Museum, IMAX cinema, Science works Museum and Melbourne Zoo.
Some alternatives to the usual things are going to the City Library, going to the Docklands to see the Mr Sandman sculpture displays and workshops; Active Zone sports workshops in Royal Park, Acrobatics and Fairy Antics at Cooks Cottage and learning about Melbourne’s wetlands guided by a Melbourne Park Ranger.
Look at
http://www.thatsmelbourne.com.au/Whatson/SFITC/Pages/Childrensactivities.aspx
for more details.