It is strange that the tradition is to speak of the "present" participle
and the "past" participle when the difference between them has nothing to
do with tense and everything to do with voice.  The so-called present and
past participles are really the active and passive participles
respectively.  As examples:

The "present" (active) participial phrase "the child eating the candy..."
corresponds to the active relative clause "the child that is eating the
candy...."

The "past" (passive) participial phrase "the candy eaten by the child..."
corresponds to the passive relative clause "the candy that is eaten by the
child...."

A change of nomenclature to active participles and passive participles
would clarify these ubiquitous constructions for our students (and
ourselves) since the standard terms are inaccurate and misleading.

Dick Veit
UNCW English Department
http://www.uncwil.edu/people/veit/DEG/