The opposite is true . One on one tutoring is easily the most effective form of teaching. No matter how capable a government school teacher is, she can not give the kind of education to each student that one on one tutoring gives. Test results consistently show that homeschoolers test at a much higher level than the government school children. Additionally, home education allows a child to receive an education that is uniquely tailored to his skills, interests and needs.
Most colleges have at least some remedial courses.
The purpose of remedial courses is to help students learn things they should already know. That doesn't sound like the government schools are doing a great job. Answer - There are many outstanding curricula available for teaching every course imaginable. They come with teacher's manuals and other materials that help the parent teach anything from Spanish to Calculus to Physics. Even if the parent is not well versed in a particular field of study, they can work with the child and learn together.