Fitbits are certainly a good option for 8-year-olds. In fact, the Fitbit Ace is made for kids 8 and up, so if your third grader loves to move—or needs some added activity incentive—a health tracker could be the perfect fit. Fitbits don’t require a smartphone to collect all that useful health data, but they do need to be paired with one if you and your child want to dive into the analytics.