Take the 427 and exit at Burnhamthorpe Rd. Exit west on Burnhamthorpe (this will be left if coming from the south, right if you're coming from the north). Proceed on Burnhamthorpe and turn right (north) onto Renforth Dr. The first right on Renforth will be Crendon Dr, turn here, and the school will be up on the right hand side past a couple of streets.
Take the Bloor-Danforth line to Islington Station. Board the 50 bus Westbound. Get off at The West Mall and walk north for a few minutes, and you can cut through Broadacres Park.