Hand Bugs (tm) are
invisible microscopic particles which when applied to hands,
will hide in the 'nooks and crannies' of your skin in much the
same way as microbes and germs would do.
After washing and
a UV light is shone on to the hands, these microscopic particles
(that have remained on the skin due to ineffective hand-washing
technique) will light-up and reveal their hiding places!
Once the correct
method of hand-washing has been demonstrated and taught, it
should be possible for the student to wash-off all the hidden
Hand-Bug particles and thereby show mastery of the technique by
having no Hand-Bug particles show-up under the UV light.