How long does it take the Earth to revolve around the sun? Did the earliest humans and dinosaurs live at the same time? What percentage of the Earth’s surface is covered with water? Think you know the answers? Well, if you’re an American adult you may be frighteningly alone.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.