Can I make a class as a teacher??
Are you a teacher?
Do you have a real class of students/pupils?
If yes, go for it, but do not make the classroom code public.
If no, do whatever you want to do for yourself (you can use it for your own to view e.g words), but please do not make any classroom codes public to the community!!
You should not be tricking normal Duolingo users into classroom settings, as the problems are going to start with that.
Any Duolingo user should not join your class if he is not a real (your) pupil and does not know you on a personal level.