Our churches, not to mention our homes and our cars, flaunt the breaking of the Second Commandment everywhere you look. Remember, kids are sticklers. When it's stuck in their face that way, they'll spot the contradictions we gloss over and they'll ask questions. Again the school is fronting the assumption that this particular Lord is thy God, whether you like it or not. A school has the right to require decorum in the speech of its students, but in a free country how I speak of the Lord my God, if I recognize such a god, is between me and my god, and it's none of the school's business.
Christians are in trouble here.
Sunday ain't the Sabbath of the God of Exodus, Leviticus, and Deuteronomy. That God, specifically and repeatedly, requires the Sabbath to begin at sundown on Friday and continue till sundown on Saturday. This was the Sabbath that Jesus observed, as the Gospels make very clear. All Christians break this commandment every week. Especially if that child is neither Christian nor Jewish nor Moslem.