If 1/3 is read as one-third, 1/4 as one-fourth,etc., why 1/1 is not one-first and 1/2 is not one-second?

Because one first (one over one) is one so there is no point in saying it...and one second is a time interval...

Dont you just love our English language. Everything make so much sense. I have a hit here, what am I talking about. Oh, he hit the ball, or he has a good record its a hit, or someone went to my web site and I recorded a hit. Yes English is the universal language, no wonder we are killing each other.

This is one of the idiosyncrasies of idiomatic English. Sometimes English makes no sense!

HTH

Charles

the same reason we sometimes say one quarter. Simplicity and commonality. Why say one first when just one means the same thing.

Math and English are not compatable

because math never makes sense and the people who thought it up thought it would be funny to mess with our minds...