It was school as usual for these pupils in Karo, Indonesia's North Sumatra province, on Tuesday, even as Mount Sinabung volcano sent up plumes of thick smoke. The volcano - which roared back to life in 2010 for the first time in 400 years - has erupted repeatedly in recent days, pumping hot gas clouds up to 3km into the sky, according to the local disaster agency. The local authorities insist that the school is safe as it is located outside a 7km restricted area around the highly active volcano. Mount Sinabung has been erupting almost continuously since 2013.