From [1] UPI:

Christian students and parents cannot sue a school district because some seventh-graders pretended to be Muslims for a history course, a court has ruled.
The 9th U.S. Circuit Court of Appeals said the role-playing game was not a religious exercise that violated anybody's constitutional rights.
The court upheld a lower court ruling, saying only that the activities at the Byron, Calif., school weren't "overt religious exercises" that would raise concerns under the First Amendment prohibition of "establishment of religion."

Would the decision have been the same if the kids had been role playing Christians, learning to say the Creed and the Our Father, pretending to fast for Lent? Why am I so suspicious?
Just so you remember what this case is about, from Dhimmi Watch [2] archives:

The Thomas More Law Center says that for three weeks, "impressionable 12-year-old students" were, among other things, placed into Islamic city groups; took Islamic names; wore identification tags that displayed their new Islamic name and the star and crescent moon; handed materials that instructed them to 'Remember Allah always so that you may prosper'; completed the Islamic Five Pillars of Faith, including fasting; and memorized and recited the 'Bismillah' or 'In the name of God, the Merciful, the Compassionate,' which students also wrote on banners hung on the classroom walls.