"My parents separated, and my father was going through some mental health issues, I never really met him, I met him one day when I was 13 and passed away when I was 14. Mum raised my sister and I as a single parent and the main job she had access to was as a cashier at a convenience store, when I was very young as she didn't have child care I remember her job was she had the keys to this vending machine and take the change out", recollects Sal Khan, the founder of the non-profit education foundation Khan Academy.
