Final answer:
Children aged 6-17 should participate in flexibility exercises several times a week as part of their recommended 60 minutes of daily physical activity, to maintain joint mobility, muscle strength, and overall health.
Step-by-step explanation:
While there is no specific number provided by the U.S. Department of Health and Human Services (HHS) for children, it is generally advisable for children in this age range to engage in physical activities that include flexibility training several times a week. This could be incorporated into the 60 minutes of daily exercise recommended for children, which helps promote overall health benefits such as maintaining a healthy weight, building strong bones, and improving cognitive ability and psychological well-being. Consistency in flexibility exercises is key for maintaining joint mobility and muscle strength.