How big is everything in the U.S!

Oh! (O_o) I found that many things in the U.S. are in bigger size than they are in Thailand. Especially this one, "chalk" in Carnegie Mellon University is very huge! From the picture, compare to the size of quarter coin, it's 4-5 times bigger! I'm curious how the teachers write on the blackboard using this chalk size. Its size is very close to the size of a big "UHU" glue in Thailand.

Another time I'll also show you the huge blackboard eraser!