You can send message to many persons in different classes. We suggesting you to follow these simple steps
Step 1: Go to EduNiv admin page
Step 2: Go to message module and type content of message in text box
Step 3: Click on address book, which is adjacent to roll number
Step 4: In that select class, now you can able to see the name list
Step 5: Now you can select students name, after that click on add selected students
Step 5 : Just close address book and send message to selected students