It is so easy to sound like a broken record or to give a hostile response to your child when they are being naughty, especially if the behaviour is reoccurring and you are feeling frustrated. You can be sure that if you give assertive responses on a consistent basis that you will get a change to your child's behaviour, for the better.
I have found that if you give assertive statements in a quiet, calm and specific manner, eg "I want you to pick your toys up and put them in the toy box in your room," or "I want you to close the iPad and do your homework immediately," your child will respond better. Assertive statements like this are easily measured and easier to reward upon completion of the parent's expectation (unlike vague statements such as "act nice," "be good," or "act your age", which are confusing to your child).