When I first started teaching my youngest class (the kids were about 5 years old), I had to teach them about global warming. Yes, global warming. Our principal didn't want us to sugar coat it, so after my lesson, one intelligent young kid asked me with a look of sheer horror on his face "The polar bears will die?" Lesson learnt.
Called Save the last Polar Bear by John Tibbot on Society 6. Pretty cool! Ice ice baby.