A child favorite around the world--Silly Putty.
I don't think there is a Continent you can go to where kids don't go nuts for the squishy, gooey, blob. It makes children happy with its farting noises and gelatinous mass.
Adults even have an infatuation with the stuff.
We took a field trip to our local Discovery Center this week with a 4th and 5th-grade class.