Abstract: A second slot is provided in the longitudinally extending shaft of a teaching tool, such as the Pneumo Pro, which is longitudinally spaced apart from the first slot of the tool, for automatically aligning the quadrant, and thereby the propellers, longitudinally and laterally with respect to the first slot during assembly of the apparatus and retaining the propellers in that orientation during usage. The quadrant and support block are formed with flat portions or surfaces which can be received in the second slot to establish a fixed point of longitudinal reference and an intersecting surface to establish a fixed point of lateral or rotational reference with respect to the first slot.