A monochrome Schlieren apparatus for use with theIntermittent Supersonic Wind Tunnel. The Schlieren apparatus allows students tosee density gradients as variations in intensity of illumination. This allowsthem to see supersonic air flow patterns around models. It also clearly showsshock waves and expansions, and students can compare their positions and angleswith values predicted by theory. The mirrors and lenses are of high opticstandards to reduce any possibility of optic distortions of the images. Theapparatus includes digital imaging equipment to record the images this isuseful when using an intermittent supersonic wind tunnel. The video monitor isparticularly useful to display the images to groups of students. The imagingequipment can capture still images and any real-time changes in the image.