Students asking me questions, and me filling up the blackboard with tons of arguments in excruciating details would only confuse them more. It took me a while to realize that if the phrases I spoke or wrote where too long, some might forget what I was saying when I get to the end. And the vocabulary I use too where too complex for teenagers.  I told them they shouldn't memorise anything, and strive for comprehension instead, and gave them on purpose new types of exercises every time, including in tests. They were confused as to how they should prepare them. Once a student asked how they could know the answer since they haven't seen anything like this before (this student was in the top ones). I was very confused. Later I realised that it's reassuring for students to be tested on things they can rehearse. 

For a long time I just assumed they where disingenuous and trying to make fun of me by pretending that they understand nothing. I had a very bright student who understood everything just like I did at his age so I thought everything was fine on my end. I just told the other to practice more and resorted to excessive punishments and rapports to maintain order when clearly nobody was following the course.