Reading comprehension is a crucial skill that is highly predictive of later success in education. Unfortunately, more and more students seem to be insufficiently apt at comprehension. Here, we create a comprehensive model of reading from recognizing letters up to understanding the sense of a sentence. With this model, we scrutinize how comprehension affects eye movements in reading, and how it is reflected in brain signals. We also model the different ways in which comprehension of a text can fail. The project results in more understanding of reading comprehension, and clues to how it can be improved in students.