Ask them 'Do you want help or company?"
Assuming one or the other can lead to the butting of heads, time wasted in frustration, and/or a misguided trip down the path of parallel intentions. Any of those, as every parent knows, are difficult to turn around and move into something more positive.
Most children from age three and up will welcome the clarification. And if they don't know, that's helpful information as well. Our job is to give our children a boost. If you are helping and they only want company, you end up with a rebellious child who is trying to stall out the interaction. If you are only offering company when they really want and need help, they are frustrated and overwhelmed which also leads to the dark alley of parent/child despair.
So ask the useful question: Do you want help or just company? It almost always leads to a better place.
Love
Deborah