Imagine a year 12 double maths class with no teacher, where instead of learning, students are sitting on their phones during class. Or a school where almost a quarter of all teachers are away. That's the reality of what some schools are dealing with as teachers complain of a severe shortage. Today, Background Briefing's Mayeta Clarke, on her exclusive access inside a classroom and why we should worry about what’s to come.Featured:Mayeta Clark, reporter, ABC Background Briefing