Keep furniture or anything a child can climb away from windows.
Only allow windows to open 4 inches and install a window stop to keep children from opening them further. (Be sure an adult can open them in an emergency).
If you open windows wider than 4 inches, install window guards that can be removed by an adult in an emergency.
Teach your children about window safety. “Screens keep bugs out; they do not keep kids in”.
Teach them to play a safe distance from windows and enforce this rule in your home. (i.e. We play 2 (big) steps away from windows).
Share this information with grandparents, childcare providers, friends and neighbors that children visit.