Burning Tigre textbooks
One of the more striking examples from Ghirmai Negash's article (see the previous entry) was how in the 1970s in Eritrea, the ELF declared illegal a school curriculum in the Tigre language and ordered all copies of the school book to be burned.
This may be an extreme example but one from Madagascar in the 1980s may be more typical. Apparently the government of Madagascar at one point needed foreign assistance to produce textbooks for its schools. At the time the instruction was in Malagasy, but when France offered aid, it was with materials in French. (Unfortunately I don't have the reference at hand). It has been noted elsewhere that the UK and US are very forthcoming with materials in English. It would be hard to say how often English, French or Portuguese materials have replaced African language ones, or to what degree their availability has been a disincentive to develop African language materials.
Even when there are materials in African languages, they are not always well distributed. The article on International Mother Language Day in Ghana (available here, and mentioned in an earlier posting) mentions:
It is however very pathetic to note that while schools complain of lack of Ghanaian Language books which affects the teachers' delivery of lessons and consequently the performance of their pupils in their schools, publications of the Bureau [of Ghanaian Languages] are locked up in our ware houses in Tamale and Accra and are not being patronised.So at least in some cases, books for learning in African languages have been burned, replaced by books in other languages, or "locked up" in warehouses. This is not even to mention those that are out of print and only available in distant libraries.
Beating or shaming schoolchildren for speaking their mother tongue
The history of schooling in Africa has many stories of how African languages were excluded from classes and school grounds (not always, but in many places) and punishments were meted out for transgressing the rule. I recently posed a question on the H-Africa list about the degree to which this is still happening. (It does still happen, but probably not as extreme as in the past.)
It is not only a question of teachers punishing students but also ways of involving peers in the punishment (see this example from a blog on Lesotho). There are some other links here (post #8).