I have been doing some research on the training of teachers, particularly in Sub-Saharan Africa. The figures make sober reading. A report 'Digital Learning: Reforming Teacher Education to Promote Access, Equity and Quality in Sub-Saharan Africa' by Bob Moon and Charmaine Villet points to the scale of the issue:

UNESCO’s Institute of Statistics (UNESCO, 2015b) has estimated that, globally, 25.8 million extra teachers will need to be recruited by 2030 to meet EFA targets (to put that in context, this is equivalent to the population of Ghana).

Of these, 3.2 million would be filling new posts and 22.6 million would be replacing teachers retiring or leaving the profession. There were 59 million children out of school in 2015. To have them all in school would require the recruitment of 2.7 million teachers if pupil-teacher ratios are not to exceed 40:1.According to the Institute’s forecasts, without such recruitment, 33 countries will not have enough teachers to achieve universal primary education (UPE) by 2030.

Sub-Saharan Africa faces the biggest challenge. of any major world region in this respect. For every 100 children beginning school in 2015, there will be 142 in 2030. And the figure is projected to continue growing at this rate through the middle years of the century. Of the 3.2 million posts to be filled worldwide, Sub-Saharan Africa will need 2.2 million to deal with this growth and, at a conservative estimate, 3.9 million teachers will be required to replace those leaving the profession.

Pretty clearly there is little chance of meeting these targets through scaling up traditional teacher training institutions, nor even through school based teacher training. That is why there is increasing interest in using technology - Open and Distance Learning, MOOCs, video and multi media, Open Educational Resources - in Sub-Saharan Africa. This development is often being led through different aid programmes run by UNESCO, the Commonwealth of Learning, USAid and other organisations. Early evaluations seem promising - although the real challenge will be in scaling up, mainstreaming and sustaining development projects. But researchers and developers working on initial and continuing teacher education in Europe and other richer countries could do well to look at what is happening in Africa.