Wow, I always thought every bad grade meant that I needed to get my child more help studying the material that they performed badly on. (Even bad teachers with fair tests can give one a chance to figure out what they are bad at teaching and get my child the help on those subjects outside of their class).

The only type of teacher that I ever had a problem with was one who was not fair in their tests. (Like seriously, it is a math test and their answer is correct but you marked it wrong because they used a different method than the one you taught in class???)