As a teacher, What do you do if the whole class is “not getting it”?

its bout time u did it other way round ...smack the whole package into smaller componenets

Vary the delivery approach and if it was ''chalk and talk'', involve the pupils and see what happens.

Question my teaching method, I have no concerns about my teaching abilities but in this instance I would reconsider my methods especially if it was obvious that it was indeed the "whole" class and not just one or two individuals.