Don't get me wrong: I do not take care of my children during the day whilst working. I'm not "working at home", I'm working, and as a general rule, my job description does not include parenting.
Once my workday is done, naturally I'm on the mommy tip, making sandwiches and the like. But during the day, I am not here. Seriously. Don't ask.
When school is out, the little kid still goes to preschool, but the big one really is big -- twelve. She's quite old enough to make sandwiches, go swimming, take a bike ride around our quiet neighborhood, and so on. But somehow just having her around all summer takes away just a little bit from my focus.
Today I put my finger on it: having someone around the house who is really in the local timezone rather than in my otherworldy East Coast existence is really distracting at a psychic level. It hit me as I made pasta with pinenuts and romano cheese today at ten in the morning. Without a pre-teen lounging around sluggishly in her pajamas, it was easy to stay in my East Coast mindset.
I know, it's a little deranged. But this is how it works for me.