You may want to let them try and work out how long it will take you to travel somewhere when you get in the car, by telling them what speed you'll be traveling and how far away your destination is.
Another important thing you must do as a parent is ensure that you are helping them with their homework. Make sure that every night they get homework, they spend time away from their friends and the television and sit down to concentrate on their work. This might seem daunting at first, but if you spend time with them and help them when they need your help, you can stress the importance of studying, and how it doesn't have to be as daunting and as boring as they think. Help them with their math worksheets every evening, whether they're working on the multiplication table or division, so that they can continue to succeed during their school career.