Oh geez.....let's see.....9 is fourth grade......3 kids 6 and under.....no, that's not right. In fact, SHE can barely handle them, right?

FOund this:
At What Age Can You Leave Children Home Alone?
You can check with your state's Department of Social Services to see if your state has a minimum age for leaving children unsupervised. You are likely to find that there is no specific age, although the common recommendation is that children under twelve be provided with appropriate supervision while their parents are away from home. There may also be a suggestion that an older sibling, even if old enough to be left at home alone, is not necessarily an appropriate babysitter for younger siblings.

There is good reason not to set a specific age at which children may be left at home alone. Specifically, no matter what age you pick there will be some children who are not sufficiently mature to look after themselves. It would not be good public policy to effectively grant parents immunity for the consequences of what they know to be poor parenting decisions, merely because a child has reached the age specified in a statute or regulation. Also, the nature and duration of the parents' absence can significantly affect the age at which the child should be left alone. A twelve-year-old may be perfectly comfortable taking care of himself after school until a parent gets home from work, but that does not mean that he's sufficiently mature to stay at home alone while his parents take a two-week tour of Europe.

Significance to Child Custody Cases
The proper care and supervision of children, including preteens and teenagers, is a valid subject for child custody litigation. While courts are usually reluctant to put undue weight on a parent's need to use child care, the absence of any supervision is a more serious concern. Thus, when making a custody decision, a court may be inclined to consider a parent's ability and willingness to limit the amount of time the children will be left unsupervised. Parents should consider exploring the possibility of before- and after-school programs, some of which are available directly through the public schools, which may be available at a reasonable cost.

Did you talk to her about how you felt?