Individuals may participate in professional development because of an interest in lifelong learning, a sense of moral obligation, to maintain and improve professional competence, to enhance career progression, to keep abreast of new technology and practices, or to comply with professional regulatory requirements.[4][5] Many American states have professional development requirements for school teachers. For example, Arkansas teachers must complete 60 hours of documented professional development activities annually.[6] Professional development credits are named differently from state to state. For example, teachers: in Indiana are required to earn 90 Continuing Renewal Units (CRUs) per year;[7] in Massachusetts, teachers need 150 Professional Development Points (PDPs);[8] and in Georgia, must earn 10 Professional Learning Units (PLUs).[9] American and Canadian nurses, as well as those in the United Kingdom, have to participate in formal and informal professional development (earning Continuing education units, or CEUs) in order to maintain professional registration.[10][11][12]