 The goal of this pilot study is to find out whether an activity meter linked to web-based rewards will increase physical activity levels in middle school aged students who use it over 6 weeks. To test this, students who participate in the study will be assigned to 1 of 3 groups: the meter with web-based rewards group, the Dance Dance Revolution group, or the control group. The physical activity of participants in all 3 groups will be tracked using the an activity meter that participants will be asked to carry daily for the 6 weeks of the study. Participants given the activity meter with web-based rewards or Dance Dance Revolution will be instructed to use them at their own will, as much or as little as they like. Before beginning the study, all participating students will be asked background questions about themselves such as their gender, age, and ethnic group and about the kinds of computer and video game consoles they have access to at home. All participants will also complete short questionnaires at enrollment, week 1, week 3 and week 6. These questions will ask participants about their experiences using the assigned devices, their physical activity levels, and their thoughts about their ability to be physically active. At the end of 6 weeks, all participants will finish the study and return their assigned devices to the study coordinator. Height and weight will be measured at baseline and at the end of the study. 