I have been lecturing basic sciences in African universities, in time when the countries of Africa have been changing their fps system to SI system. A very interesting and challenging period! It took some years to accomplish the change fully.
Surprisingly, the change was more visible and easier done in business (packaging, volumes, balances), shops and streets (kilometer posts, speed signs, change to a right hand drive) than in a university laboratory. Why did they succeed in relatively smooth way? You may say that if "there is will, there is a way". Although, it is true, the countries were less developed and the changes had not met big resistance. It required mobilisation of civil organizations, business and government institutions including police. At that time there were some good core physics books for science students. However, most of them were written by English and American writers using fps system. There was no book for students on experimental science, where all quantities were to be measured and the answers expressed in SI units. Students did not know how big is a meter, what "nano" or "giga" means. By the same token there was no "conversion” fear, so hampering introduction of SI in USA. You may compare learning a new system with a learning of a new language. Does it require constant "conversion"? The problem shifted to mathematical manipulation of the power of ten notation, SI prefixes, SI units, inter-conversion within the metric system, accuracy, precision and the uncertainties of measurement or calculated quantities. This prompted me to write the book for students of science and engineering courses on experimental science: "SI Units Conversion and Measurement Skills". If you wish to learn about the book, please visit my website: http://www.wacek.co.za.
Wacek Kijewski