My DC's primary school sets a tonne of homework every evening. Usually WhatsApp is pinging away as people in my mums group ask for photos of books their DC have forgotten/ask for dates of tests etc.
Irritatingly Id posted on the class group asking if anyone has seen DS1's coat (one of his bullies has hidden it grrrr) before seeing that it wasn't working.
Phone or texts are fine for 1:1. WhatsApp is brilliant for group messages