but research evidence clearly points to the importance of ensuring professional learning opportunities are sustainable darlinghammond et al this is endorsed in the professional lear ning community and other related literature rosenholtz louis kruse et al stoll et al strong performing education systems like those of singapore and japan have institutionalised this good practice and have put the majority of professional development resources as close as possible to the point of use in singapore for example teachers are entitled to hours of professional development each year the majority of professional development is provided on site in the schools where teachers work and is directed at the specific goals and problems teachers and school leaders are addressing in those schools