Khan Academy
Khan Academy: Brain Teasers: Toggler Brain Teaser
Separating the truthteller from the togglers!
Khan Academy
Khan Academy: Brain Teasers: Blue Forehead Room Brain Teaser
What happens when 100 perfect logicians have to figure out if they each have a blue forehead?
Khan Academy
Khan Academy: Brain Teasers: Light Bulb Switching Brain Teaser
Turning light bulbs on and off.
Khan Academy
Khan Academy: Brain Teasers: Alien Abduction Brain Teaser
Saving Earth from becoming a mushroom farm.