Thus by 1803 there were two known rare earth elements, yttrium and cerium, although it took another 30 years for researchers to determine that other elements were contained in the two ores ceria and yttria (the similarity of the rare earth metals' chemical properties made their separation difficult).
For instance, students who pursue a Ph.D. in psychology usually take from five to seven years depending upon required coursework as well as internship and supervised residency requirements.
Doctor of Education Program Overview. A typical doctorate degree program in education takes approximately three years to finish, although more specialized education degrees, like a Doctor in Science Education, can take as many as seven years to complete.Candidates need to hold master's degrees in education to meet program entrance requirements. doctorate degree in education is a terminal degree in many fields, and the length of time it takes to complete depends on several factors. There are several educational paths you can take to earn this degree. View 10 Popular Schools Â».