...
Select the option the school will be using more out of SMS or Email. If you vary messages and it is roughly 50/50 then select both SMS and email. This can easily be changed while sending a message and will not limit you to send sending one or the other.
Receiver
This will decide who the messages are sent to. It can be changed on a message - by - message basis if needed but the main option most schools use is Parents or other contact. With this option selected, it will also send messages to staff if staff have been selected.
...