Hi, I suggest contacting your child's teacher or school directly for accessing your child's grades. If located in the U.S., you can use SchoolFinder to quickly access the school's phone number: http://www.education.com/schoolfinder/
Some teachers and schools do have websites with information for parents. Ask your child's teacher or school if they have a website with grades posted. Given confidentiality concerns though, if your child's school or teacher does offer a website with grades, there will likely be an access code or login information you'll need to privately access your child's grades online.