... Policy-level constraints included poor communication of key messages [39,42], which often led to inconsistency of understanding of key concepts [43,44], a lack of time to cover the curriculum [30,36], and examinations that contradicted the changes [35,45]. Regarding teacher recruitment and development [46], constraints included a shortage of qualified teachers [37,42], poor working conditions [36,40], insufficient teacher training [37,39], short and superficial teacher training [43,47], a lack of follow-up to initial sessions [34,48], passive, unengaging training [37,48], a lack of practical experiences [40,41], a lack of flexibility to adapt to the context [37,44], and a lack of opportunities for teachers to collaborate [41,43]. Conversely, more successful teacher training experiences were those that were longer, incorporated ongoing support [49,50], were active and engaging, incorporated practical experiences such as observation and teaching practices sessions [33,51], included opportunities for teacher collaboration [51,52], and incorporated opportunities for teacher reflection, especially regarding the flexibility and autonomy to adapt learner-centred principles to their own teaching contexts [50,53]. ...