For 50 years Anna Scher has taught acting to north London children, with many " such as Kathy Burke, Daniel Kaluuya and Adam Deacon " becoming household names. What is it about her approach that has brought so much success?Jake Wood was nine when he first met Anna Scher, and he didn't know what had hit him. "She was just this whirlwind of energy. I was like: 'What the hell is that?' I'd never met anybody with th…