Simple Machines Screw Model US-Unavailable with adjustable slit and draw-out

with adjustable slit and draw-out focusing for examining the spectral composition of light sources

taste-bud zones

Pairs 50mm of aperture with a 200mm focal length on a convex glass surface

Double-concave glass lens at 3-inch diameter and 200mm diverging focal length

Miniature desktop torso with 12 removable parts includes a dissectable head and brain for compact classroom anatomy and biology teaching

Simple Machines Screw Model US-Unavailable with adjustable slit and draw-outSquare topped wooden screw simple machine model with a leverage block, letting students measure rotational distance against linear advance to derive the mechanical advantage of the spiral.