Final answer:
The correct way to fold letters for standard window envelopes is to fold the letter in half and then fold it again.
Step-by-step explanation:
The correct way to fold letters for standard window envelopes is to fold the letter in half and then fold it again.
This ensures that the address is visible through the window of the envelope.
Folding the letter in this manner allows for efficient mailing and easy identification of the recipient's address.