This document discusses physical activity milestones that children should reach between ages 3-6. It notes that while most children reach skills like balancing on one foot or hopping within certain age ranges, all children develop at different paces so parents should only be concerned if a child cannot perform most skills beyond the age when 90% of children can. The document aims to ease parents' worries by providing benchmarks on normal development while also advising them to consult a doctor if their child is significantly delayed. It emphasizes that creating a safe environment for children to explore movement is important for developing lifelong active, healthy habits.