A tornado warning in the 1970s came with different action statements than tornado warnings do today. One of the biggest differences is the idea that you should open windows to prevent pressure damage. This is a myth.
Opening your windows does not reduce the damage from a tornado. In fact, a study done in 1979 showed that homes open windows and doors usually fared worse in tornadoes. That's because most of the damage is done by the wind getting inside the structure. Tt also takes valuable time to go around your house opening windows. That is time you could be using to get yourself and your family to a safe place to ride out the storm. Tornadoes are serious business, and there is no time to lose when it comes to your reaction to a tornado warning.
Forget about the windows. Find a spot in the structure on the lowest floor or basement, near the center, and away from the windows. That's where you'll find safety.