Lemonade Frosties

What are the parts of fans that swing and rotate called...? I didn't have that as a word in third grade vocabulary. I can't think of it...is there a word? It's making me nervous not knowing. Fans are so intimidating as it is; when they're tunred on they are beasts. So, I won't ask them. Not that it's vital knowledge, but I have the feeling the fan across the room is staring and if he jokes about me not knowing, I would like to come back and say I do know. Mostly because I don't like conflict - especially with fans.