Computers can be a great tool, but a group says overuse causes children to have lower grades, weight problems and other issues.

So the PC-Turnoff Organization wants members of Generation M -- those 8 to 18 years old -- to stay off the keyboard from Monday through Aug. 7.

The group says that excessive computer use also causes social isolation, attention problems and a stress-filled family life. Getting away from the screen improves communication, allows for more outdoor play and encourages reading, the group says.

PC-Turnoff also says that employed fathers spend an average of 2.3 hours per day caring for and doing things with their children, and employed mothers spend 3.2 hours per day with their children.

Generation M kids spend 6 hours and 21 minutes per day with computers, the group says.