I live in a non-Muslim country and try to help the Muslim youth (age 12-16) to save their faith in this society (which contains a lot of promiscuity, pre-marital relations, alcohol, and so on). Once a week, I gather some Muslim youth for a small lecture (usually about the biography of our beloved Prophet, sallallaahu ‘alayhi wa sallam), and they are merely spending time under my supervision. Usually, they play some educational games; we even have a bow, and they are mastering the art of archery. Spending time together is extremely important for the youth given that the human being is a social creature, and we have to provide our youth with an Islamic company, otherwise they will seek an un-Islamic one. Unfortunately, only very few youngsters attend these gatherings, so boys and girls come together. Of course, I am trying my best in order to maintain the Islamic etiquette. So I have two possibilities:
1. To continue my Da'wah (proselytization) in this direction and hope that one day we will have enough youngsters to have separate-sex meetings.
2. To end this type of volunteer work. If you were to tell me to continue, then could you give me some fruitful advice? On what should I focus?

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.

Firstly, we would like to commend your efforts and keenness on carrying out righteous deeds and instilling virtue within the Muslim children. May Allah reward you generously.

If the children have reached puberty, then it is impermissible for the boys to mix with the girls. As for young children who have not yet attained puberty, they should also be separated so that they would become accustomed to it, as we have previously underlined in fatwa 85641.

But you should know that just being under the same roof is not considered prohibited intermixing. If there is some sort of separation between them, even in the same hall, then this would not be prohibited intermixing. The Kuwaiti Encyclopedia of Fiqh reads:

"Intermixing between men and women is allowable for a need recognized by the Sharia provided that the relevant Sharia provisions are observed. This is why it is allowable for the Muslim woman to attend the congregational and the 'Eed prayers. Some scholars underlined that it is allowable for the Muslim woman to perform Hajj escorted by a trusted group of men. It is also permissible for the woman to engage in transactions such as buying, selling, renting, hiring, and the like with men. Imaam Maalik was asked, 'What is the ruling on an unmarried woman who seeks the help of a non-Mahram (marriageable) man to carry out some tasks for her and hand things over to her?' He answered, 'There is no religious impediment to it; and I prefer that he lets another accompany him. Were people to neglect her, she would be helpless!'"

You should try in the future to separate them so that each gender would be alone, and some righteous female teachers should teach the young girls. Verily, this is better and safer.

Allah knows best.