I would respectfully challenge your claim about references to God in the feminine - recalling that the spirit of Wisdom of the old testament is closely associated with the Holy Spirit of the trinity.
From the book of Wisdom:
"Resplendent and unfading is Wisdom, and she is readily perceived by those who love her, and found by those who seek her. 13 She hastens to make herself known in anticipation of men’s desire; 14 he who watches for her at dawn shall not be disappointed, for he shall find her sitting by his gate. 15 For taking thought of her is the perfection of prudence, and he who for her sake keeps vigil shall quickly be free from care; 16 Because she makes her own rounds, seeking those worthy of her, and graciously appears to them in the ways, and meets them with all solicitude. 17 For the first step toward discipline is a very earnest desire for her; then, care for discipline is love of her; 18 love means the keeping of her laws; To observe her laws is the basis for incorruptibility; 19 and incorruptibility makes one close to God; 20 thus the desire for Wisdom leads up to a kingdom. 21 If, then, you find pleasure in throne and scepter, you princes of the peoples, honor Wisdom, that you may reign as kings forever. 22 Now what wisdom is, and how she came to be I shall relate; and I shall hide no secrets from you, But from the very beginning I shall search out and bring to light knowledge of her, nor shall I diverge from the truth. "
The original poster said something about confusion of the teenagers - especially the teenage girls. I suggest that part if not most of that confusion comes from an inability of most teenagers to imagine anything without gender. Part of their education should be to learn that gender is not the greatest factor in a persons identity. Refering to God as feminine, while not strictly accurate, may be a step towards their learning that.
I have no what the true agenda is of the volunteer teacher you are working with is, but the idea of refering to God as feminine is not without precedent.
peace
-Jim