The Professor comes face-to-face with an Australian koala - and learns not to call it a koala bear. And as always, it's a chance to talk chemistry. Our thanks to Cleland Wildlife Park in Adelaide, South Australia, and to Hank the koala. More chemistry at http://www.periodicvideos.com/ Follow us on Facebook at http://www.facebook.com/periodicvideos And on Twitter at http://twitter.com/periodicvideos