I know this isn't practical but often children are MUCH better behaved if a member of the extended family pulls them into line. I don't have the best relationship with my mother but I know that when she is staying with us that my kids don't act up quite as bad. Gaurenteed if a grandparent was sitting at the table having a cuppa my 6yo DD would have more likely to do the right thing... all it would take would be for Nana or granDad to say "Listen to what your mother is saying" for them to comply. Sadly this is where the modern nuclear family really suffers... kids are just tuning out... mum's voice just becomes a background hum... too constant... too predictable... broken record mum. Sometimes doing something out of "left field" can work to keep their attention. Say things a bit differently... whisper instead of shout... say something ridiculous "And when you have finished brushig your teeth go and check if there is an emu in the backyard". Say it dead pan. It's a common teacher strategy