We only know a little about Mary and Martha (and their brother Lazarus, who we encounter later on). They are apparently people who met Jesus at one point and became friends with him. They know him well enough that when he travels through their village, he stays with them. Considering the hospitality codes of their culture, this speaks of a much more intimate relationship than we would ordinarily think of people we call "friends" -- maybe even something more like family.
I'm only guessing here based on what we do read about them, but I think Martha was the eldest child. The culture might not allow her to inherit as her brother would, but culture means bupkis up against the oldest child syndrome, and Martha has it in spades.
When we meet her and her sister Mary in this story, she is performing the proper duties of her role as a hostess. She's making sure everyone has enough to eat, enough to drink, the dishes are being taken away when they're finished, that everyone's seat is OK and that no one needs anything. Even if she's just supervising others doing the work, it's a busy task. Before we go on, we should understand that Martha's actions themselves are not the problem. Sometimes people suggest Jesus reproves her because she's spending so much time on everyone else and none on him. But the idea wouldn't make sense to anyone in this story: The hospitality codes made it the host's or hostess's duty to tend to the guests. The purpose was to make the guest feel welcomed and at home. Remember that Jesus himself called out Simon the Pharisee for omitting some of those same courtesies when he hosted the Lord and his disciples.
Where Martha goes wrong, I think, is that she mistakes the things she's doing as the point, instead of understanding that they are a way to get to the point. She has become so distracted by her many tasks that she forgets the tasks have an ultimate purpose: Making guests feel welcomed and at home. Because of this distraction, she's overlooking that Mary is doing exactly that by listening to Jesus speak: She's paying attention to the guest of honor.
My own belief is that too often, we use this story to beat up poor busy Martha for not slowing down and taking time for Jesus (Yes, I am also an oldest child. Why do you ask?) We need to do less and be more. OK, sure. That's probably the case for almost everyone and there is plenty of good in finding a better mixture of doing things for Jesus and being with Jesus. I think a more useful lesson is not to allow ourselves to let either our being or our doing distract us from the why we're doing it.
Businesses and corporations -- and these days, most everybody -- seem to be big on mission statements. Almost everywhere you look, someone has developed a new mission statement or is developing one or maybe rethinking an older one. Some of the emphasis is silly, a way of trying to catch on some kind of trend or shake up a complacent environment or work force.
But good mission statements are very useful. They answer the questions, "Why are you here? Why are you doing these things?" If you want to accomplish something, those are good questions to ask and even better questions to have answers for. It's good to ask them again before a new task or project. Does the task directly contribute to our mission? No? Then why are we doing it? And it's also good to ask them "mid-project" sometimes, too. Are we doing these things for their own sake, or are we still doing them for our overall mission?
I think Martha had fallen into that last problem. The tasks of hospitality distracted her from the purpose of hospitality, so she failed to see that Mary was performing her role as well. The whole family had a role (we don't see Lazarus here, so maybe his role was grilling the burgers), and together they made up the welcome that the guest had a right to expect.
It's easy to do this as a church. To forget that committees, Sunday school classes, projects and just about everything else aren't supposed to be ends in themselves, but are ways to get to an end. It's easy to do this as individual Christians, too. To forget that Bible study, prayer, worship attendance and just about everything else aren't important unless they have as their goal our growing closer to God and conforming our lives to his call.
Because otherwise, there's a lot of other things I could be doing on Sunday morning.