how do you encourage your child to study harder?

I help my children with their homework and studying for any tests they have. I think my involvement with their studies encourages them to work their hardest. I always praise them when they do a good job, and on the rare occasions that their marks aren't very well, I tell them so long as they tried their best, this is all that is important. And I tell them we'll just study harder next time. I don't feel I have to pressure my children to do a good job, it is something they are proud of doing on their own.

promise a reward will make your child more attentive to their studies. but not always to prevent abusive demand from them.