Four classes, four rows, and 1 + 1 + 1 + 1 = 4 = h. Step 11 of 18 of the symmetry tutorial, worked in a live 3D view. Change any of it and the view follows.
Molecular point groups with their operations and character tables, the 230 space groups with a cell builder, and the 17 wallpaper and 7 frieze groups drawn live. The tool needs JavaScript, and WebGL2 for the 3D views; these are the pages it offers: