I remember being told in fifth grade that we had to learn the metric system because everything in the U.S. was going to shift over. That was a long time ago and the only time I remember it really being pushed on us was at the gas pumps, how did that work out?
An interesting side note is the catastrophic end to the Martian Orbiter in a joint venture with US and Europe. While the landing team in Europe was providing changes in speed and distance that was in Metric, their US counterparts measuring with our system, causing the spacecraft to crash when it got to low in the atmosphere.