What do you feel is the most effective way to communicate with parents?

meeting with interaction 

Yes, communication is very important in today's world.

To pass concrete messages through their child, massages that are sound and clear that their child is making good progress in knowledge,skills and attitude.

phone calls

hand written letters

Email

Some big schools in India are using school administered portals and forum with unique id and password.Ideally,parents are expected to keep the password intact.in every PTM the login details are updated by the IT dept.Another ways can be meet-ups,guardian workshops,fortnightly catch ups in case of primary and secondary schools

among O level students parents generally can't keep up with the forums and workshops so direct channels like office or second address intimation in writing or email brief-ups..Telephonic applies to urgent cases at all levels

Listen, smile, nod, do your way

Of course, there is nothing better than personal meetings, but if the distance does not allow you to do this often, then only messaging remains. I don't really like this method, especially after I came across an article https://celltrackingapps.com/clone-a-cell-phone-to-see-text-messages-for-free/ I would not want someone to interfere in my personal space and read my messages, so I am very selective when writing text messages.