I can tell you, that as late as 1979, basic slide-rule
was taught (using the
aforementioned six-foot-rule) as part of "Introduction to Scientific Method"
which all freshmen had to take at my high school. The rationale was that it
taught students to effectively read scales, and to interpolate values between
tick marks. It also gave them a sense of what a log scale was, and how values
were represented thereon.
Another great advantage of slide rules (educationally) is tht they give
the mantissa and not the ecxpnent. In other words the user genrally has
to do an order-of-magnitude estimate to be able to correctly interpret
the slide rule result (there are rules for doing it by rote, but it is
easier to do the OOM estimate IMHO).
Being able to do such an estiamte is a very useful skill and avoids
sillies like the 'genius' who told be the period of a swiming pendulum
was a few nanoseconds (!)
-tony