We have this issue with my two. Making it a game and using timers has been a help. I would not dress my kids, though.
I want to get one of those visual timers that show green/yellow/red but they all are expensive or have bad reviews.
Because time is at a premium in the mornings, we pick out clothes, pack backpacks, and otherwise have everything done the night before. They may not have breakfast till they are clothed, hair and teeth brushed, shoes on. This might not work if your kids aren't big eaters! (mine are)
