Go to the zoo anyway, with your daughter. Try to stay as close to your son’s group as possible. Make sure the teacher has your cell phone number so you can be there in minutes of for some reason you happen to be at different parts of the zoo.

As for friends with emergencies interupting homeschool, I’ve had to deal with that on occasions, but it really boils down to how much importance you yourself place on what you’re doing. They wouldn’t ask a friend who’s a government or private school teacher to stay home from work to watch their kids would they? We were discussing this general problem in our Sunday School class a few weeks back -- people who do not hear "no." We’re on a series based on the book "Boundaries" and the conclusion was to learn the boundary of your responsibility. As in the old saying, poor planning on someone else’s part does not constitute an emergency on your part.