Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Gifts students filling the cavity with

students filling the cavity with water or other liquids to study Snell's law and refraction-index variation by medium

Brass-knife single-pole single-throw switch on a durable plastic base

Compact metal-box convection demonstrator at 10 by 4 by 3 inches with two glass chimneys

walls revealing fluid levels behind the depth-dependent pressure jets

Ten-pack of 5mm green through-hole LEDs

Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Gifts students filling the cavity withOptically worked double concave glass lens at 75mm diameter and 150mm focal length, the diverging curvature producing virtual upright images for refraction and beam spreading work.