History's a Mystery. Hystery's a Mystery series, #1

Matt, Ben and Nicky have grown up together in the small town of Coolongawong. Now they are about to start 5th class with the school's most popular teacher, Mr Mac. On the first day of school a new girl joins their class. Kris can't forgive her mother for bringing her to this small town out the back of woop-woop and is determined to hate her new school. But all that is quickly forgotten when, together with her three new friends, they discover that Mr Mac's classroom is a magical one and they can go on the most amazing adventures within it.
By tripping on a creaky floorboard and saying some magic words, they can be transported back in time and discover history as it is being made in exciting, and sometimes dangerous, adventures. Mr Mac's love of teaching history provides most of the destinations the four friends choose to visit. Together they meet some of history's most famous heroes, and are present at some of history's most crucial times.
Their adventures take them from Ancient Egypt to Pompeii, from Antarctica to Japan and from Camelot Castle to the Eureka Stockade, with many more places in between.