ClassMate

Simple, Ad free and easy to use. Just install the app and create a account. If you are a class-representative or class-captain then, simply create a class and invite your classmates to join. If you are not a class-representative then, join the class using the class-code given by your class-representative. Class representative can add/update class routine, can add message about schedule changes or others, can add/remove important links, can block suspicious classmate of your class. Everyone who are in a class can access all the info of that particular class only. Everyone will be notified as soon as any schedule changes by representative. You can access your classmates info and can call/message/mail them.
Your information is secured. No one can see any info except those who are in your class. Only you can change your personal info. There is also manual verification to prevent people from accessing your class info.