I would say that a high effectiveness, especially for the recruiting and training of teachers along high standards in pedagogical skills and their resulting competence in teaching and communication with students is very important for education. The claims demanding by the subjects to be treated will become more and more complex and interdisciplinary, and teachers have to be very flexible to keep pace.
The Finnish system of education is a very good and well proven model for orientation. Finnish teachers must meet strict requirements and selection processes but the high scores of Finland in cross-national school assessment studies like PISA, TIMSS, PIRLS etc. show that show that it is worthwhile.
As literature I want recommend:
Popa, C., Laurian, S. & Fitzgerald, C. (2015). An insight perspective of Finland’s educational system. Procedia - Social and Behavioral Sciences, 180, 104-112.
and
Baskan, G. A., Yıldız, E. P. & Tok, G. (2013). Teacher training system in Finland and comparisans related to Turkey. Procedia - Social and Behavioral Sciences, 83, 1073-1076.
To my understanding, 21 century learning is about knowing the world beyond classroom wall. As we embrace technological innovations, learning require education setting to teach the so called labour-demand-driven skills by enforcing the use of technology to solving societal problem, imparting digital skills, employing e-learning and blended learning.
However, the use of social networking, e-learning, online learning describe in details how 21 century can be defined. Students indeed need freedom on their way to learn, parents need to reduce some education cost by employing technologies, teacher need professional development to maintain their status.
In this regard, teaching and learning in 21 century is enjoyable.