I know from my own education that the information understood from traditional lectures is usually much less than what the teacher is trying to convey. This is especially true in "hard" lectures such as mathematics and physics.

Therefore me and a group of students created a tool for the teacher to visualize how many of their students understand what is being said at every moment of the lecture.

Now we're starting to wonder if this is a problem for other students/lecturers/schools as well. What is the efficiency of a lecture? How effective is the transfer of information? How large proportion of the students do actually understand what the teacher is talking about? Is there any research which has tried to estimate this?