I have had lessons with teachers from 96 different countries.
I have had English classes with teachers of 96 different nationalities.
ーI have had lessons with teachers from 96 different countries.
「９６カ国の先生とレッスンをしました。」
teachers from 96 different countries「９６カ国の異なる国々の先生」を使って表現しました。
ーI have had English classes with teachers of 96 different nationalities.
「９６カ国の国籍に先生と英語の授業をしました。」
teachers of 96 different nationalities「９６カ国の異なる国籍の先生」を使っても言えると思います。
ご参考まで！
カナダ 
