kana - Why does ちょうし translate to "choushi"?

I apoligize for the dumb question, I just started learning recently.

But I'm using memrise to help me learn Japanese, and what I've learned is that ち = "chi", ょ = "yo", う = "u", し = "shi".

Based on that, wouldn't that translate to "chiyoushi"?

Or does ち mean "chi/ch", and ょ mean "yo/o"?

Thanks!

Answer

ちょ is what we call a digraph; notice that the よ is small, not full-sized. If you wanted to write "chiyoshi," it would have to be ちようし, not ちょうし. I'm not going to list every digraph and their Romanizations/pronunciations here because there are tons of them, but if you check the Wikipedia articles for Katakana and Hiragana, there should be a chart of all of them.