why a menorah? I thought it was not supposed to be an idol-like symbol, but something seen from a window or kept inside. Were there menorahs in school when you were 7?
If anyone complains about the Christmas tree in school you might want to point out that it is an ancient practice whose origins are unrelated to Christianity. That a particular religion has tried to take it over as theirs should not be grounds for its prohibition.
If worse comes to worst, perhaps it can be salvaged by putting up a display called "Winter Solstice Celebrations in History."
There is a fine line between government promotion of religion and government suppression of it, with much argument over exactly where to draw that line.