What would you do if a child got cut badly on a tricycle?

Depends on how deep the injury is. If it is a fairly deep cut then you would want to wrap it and go to the hospital. If it is more on the surface you want to clean it with soap and water and dab it with paper towel and then put rubbing alcohol if available.(It will sting some) Then find a decent sized band aid and put on the area after you dry it by dabbing paper towel quickly.