When the children in an elementary class prepare to go outside for physical activity, the time savings and tidiness that clothing affords will prove to be a great advantage over total reliance on sunscreen.
If the shirt is lightweight and well ventilated, it should not cause overheating. However, during extremely warm weather, sunscreen could be used instead.
By wearing a hat and covering the arms and legs with clothing, sunscreen need only be applied to the lower face, neck, and backs of the hands. What a great savings in both time and cost!