Even if there is a school guard posted, it is important to follow the law and not cross the double yellow line. The school guard is there to help students cross the street safely, but they cannot always control the actions of other drivers.
If you need to turn into a school, you should look for a safe place to cross the road, such as a crosswalk or an intersection. If there is a double yellow line, you should not cross it, even if there is a school guard posted.