I am editing an article by a non-native speaker who is using the expressions:
1. what is to be learned
meaning the things that the students are expected to learn or that which is to be learned
2. what is possible to learn
meaning those things which it is possible for a student to learn in a particular situation
3. what is made possible to learn
in the following sense: the teacher (or circumstances) make it possible for the student to learn X so X is "what is made possible to learn"
The first of these phrases seems grammatically correct to me, even though it is a bit awkward.
The second two phrases sound wrong to me but I am having difficulty analysing exactly why they don't work (particularly in the case of "what is made possible to learn".
The main problem seem to be that one can't say "X is possible to learn": that we need to say "it is possible to learn X", so "what it is possible to learn" would probably be better. But I suspect there is another problem with the third sentence - I just can't put my finger on.
I would really appreciate if someone could help me to understand exactly what the problem is with these constructions and, if possible, suggest an alternative.