I used to tutor adults in literacy. One of my clients told me that at times he ended up in the women's restroom simply because he didn't recognize the word on the door.
I hadn't given much though to that until he had mentioned it to me. Most restroom doors do seem to have a silhouette of some type to go along with the text on the door; but apparently not all establishments have done that.
If you see any restrooms that don't have a proper image to go along with their words, be sure to let the management know. Restrooms should be recognizable by all people, whether it is an adult literacy student or by someone from a foreign country.
There are also restrooms that are meant for both men and women; they are usually family restrooms.
Otherwise, they are usually meant for one or the other.
And do also work with your students to recognize the various sight words for men and women that are used in your local area.