My kids also go to a charter school, and our requirement is also 15 hours. I'm the volunteer coordinator, and take home work is our biggest request.
I do my best to honor the take home requests, but sometimes there just isn't enough to go around.
We have pizza day, and this is probably our second most popular event for volunteering. We have many parents that come to help and also have a child on their hip. This may actually be something for you to consider. It will get your little one used to the school surrounding, you will meet other parents, and you'll have a blast. If you don't have a pizza day or the like, volunteer in the classroom a couple of times for class parties. You can spend as little or as much time as you like, and still reep the benifits.
I can't tell you how many hours I spent at school with a young child on my hip while I was helping in the classroom for my older child. It is a little more challenging, but I'm glad I did it.
All charter schools require hours. Here in Florida, we can actually legally ask a family not to return if their hours have not been fullfilled. It's written into every charter. So please make sure you get your hours in.
You're probably not the first parent with challenges they prevent you from being as involved as you would like. So talk to the appropriate personel at school so you can make sure that you and your school can both benefit from your volunteer time!!!