Testing plans
When I do my day job of a CS teacher, I teach kids to code. We teach 4 key principles: plan, code, test, evaluate.
Seriously. DO YOU EVEN TEST ANYTHING YOU DO. If you annouce a change, surely the generalised theory is "sure of course they tested it works, we wont have to cancel a whole week of AQ". To keep this "constructive" if you would like feeback I'm happy to offer it but I'll once again go to my default of:
actually...test...your...code