How to estimate proficiency of concepts with log student ?

[Holmes2002]

I want to ask about proficiency of concepts in NeuralCD, in paper have visualized how much student master each concepts but in training and evaluation just for question-next prediction ?

[Holmes2002]

Hm seem that proficiency of concepts is embedding for training...

[Holmes2002]

I have another question that in MOOC system how to evaluate proficiency of concepts in case new students register system due to fix and use student id in training ?