In March of 1974, Professor Herman Koloseus¹ arrived in class at the end of the Winter Quarter at Colorado State University, and announced that the final exam in Open-channel Hydraulic] was going to be quite different this time. We, the students, who numbered around fifteen, were to prepare our own questions and proceed to answer them. He would grade by judging meaning, content, and accuracy, and assign a grade accordingly.

My recollection of the events has faded a bit over the years, but I remember clearly that we all complied. We submitted the self-prepared exam, and waited for a grade... and waited, and waited.... About a week later, Prof. Koloseus showed up, visibly exhausted, acknowledging that it had taken him quite some time to grade the exams. After thanking everybody for their efforts, he went on to say that the experience had been so demanding of his time and energy, that he vowed never to do it again.

Roll waves forming in a steep lateral canal when the Vedernikov number V ≥ 1; Cabana-Mañazo irrigation, Puno, Peru.