I realized many international students have problems with coins in here.
They are curious about why there are no number on coin and why dimmer are smaller than nickel. I totally didn't realized it since I learn about coins by bitter experience. When I was secould grade in elementary school of America, during P.E class, one student approached me and asked me whether I can give some of money pointing a big coin on my palm. Of course, I said "no!" thinking why am I have to give her money even I don't know her. She didn't forgive. She pointed the smaller coin and asked me whether I can give it to her. I gave it, since it didn't seems like big money. She brought the coin to snack bar and bought gums. When I saw she is chewing the gum, I also want to buy gum. I went to snack bar and handdle the bigger coin to casher. She only give me 5 gums. I asked her why she give me 5 gums even she give 10 gums to other girl. What I got was 5cent, the bigger one, and what the other girl got was 10 cent, the smaller one.