A teaching aid for players of brass instruments is described that includes at least one rectangular paddle connected to a handle at one end. The rectangular paddle is dimensioned to have a height appropriate for a type of player's instrument so that when the rectangular paddle when placed between the front teeth of the player, it holds the teeth apart a distance equal to the height of the paddle, that distance placing the player's mouth in a proper position for that instrument. The handle is preferably sized to fit through the opening in the mouthpiece of the player's instrument.