Bad Grades = Punishment

I'd like to get some insite from parents of teens or preteens on grades and punishment. I've heard a lot of kids say that they got their cell phone or computer taken away for a bad grade or they were grounded. One of things that I don't understand is that they get this consequence for a few weeks but the semester is 5 months long. I guess I'm most curious to know if this is effective in improving the child's grades. I don't punish my children for bad grades, they were taught the importance of good grades but I strived to teach them to care about their grades. They have made mistakes or been lazy but I've not punished them for it. I've discussed it with them and they know the consequence for being lazy and irresponsible is a bad grade on their report card. Which actually bothers them and they typically feel disappointed in themselves and they feel they let me down. They then self motivate to improve their own grades. I dont' feel the need to punish them. Do you have consequences for bad grades? If so what are they? Has it been an effective way to get your child to improve their grades?

Put the internet to work for you. via Personal Recipe 2629979