I found Lippmann's article on teaching the concepts
of measurement both interesting and illuminating:
R. Lippmann Kung
"Teaching the Concepts of Measurement:
One example of a concept-based laboratory course"
Accepted for publication in Am.J.Phys.
Preprint online at:
<http://www.physics.umd.edu/perg/papers/lippmann/>
There was some discussion on pendulum swing in the
earlier thread (Reaction Time (was Re: Human Error?)).
Incidentally, Lippmann takes a pendulum swing as
an example: she states that "it is better to start
and stop the timer when a pendulum swings through
its lowest point..." (see note 24 in the article above).