First of all research whether or not you are allowed to homeschool another person's children in your state, links can be found here on each state http://homeschooling.gomilpitas.com/directory/Legalities.htm  In most states it is NOT legal to homeschool children other than your own full time.

That being said many homeschoolers do have their kids participating in classes or other educational opportunities at one point or another run by another homeschooling parents, cooperative homeschool group, teacher or tutor so that could be an option for what you are doing.  

Legally if you are teaching a group of kids full time you are a 'school' and you should look into the laws and legalities of running this as a business out of your home.

There are many creative and legal options to run your classes the way you want-perhaps looking into it as a business is the best way especially in regards to liability insurance and days of illness or necessary leave.