“When {child_name} gets cross or upset, can {he_she} usually calm down with a bit of help — name what's wrong, wait, work towards what {he_she} wants?”
Follow-up: “Can {he_she} follow a small string of instructions at home, like 'go upstairs, fetch your jumper, and put it on'?”
Naming feelings out loud — yours too — is the single most useful thing you can do.