Optics allows users to simulate standard optic elements (lenses, mirrors, dielectrics, sources, apertures) and observe the ways that light rays propagate through these elements.  This Physlet is also scriptable, but some physics teachers have provided instructions for the default optics bench (shown below) in order to incorporate it into tutorials.  Element properties, such as position and focal length, can be adjusted using a click-and-drag metaphor.

Curriculum authors should point out that this Physlet uses a thin-lens model.  This model does not include aberrations and bends light rays at the center of the lens rather than at the surface.  Aberrations can be demonstrated by construction a lens using two changes in index of refraction.