Ah, non-sexist calling.
If I'm calling at a gig with a lot of children, I try to do dances where gender is irrelevant. And I might suggest in e.g. a 4 couple longways dance, that the small people have big people alongside as well as opposite (though any child old enough to know R from L may well be a better dancer than many adults).
If I'm with occasional dancers they often expect men to dance with women, so I'd build on that but make sure they know they needn't.
For beginner I'd say "a line of men,or ladies dancing as men, with their partners in another line facing them". And I'd tell them whether it mattered which side they were on (in many easy dances it doesn't).
Scoville - ceilidhs use a variety a forms, squares, longways for 3/4/5/6/8 couples, contras (for experienced dancers or ambitious callers), single/double or triple circles, and more.