In first-year engineering students, a common teacher-centred, passive learning and deficient secondary educational backgrounds are often observed. However, there is a problematic difference whether the individual background is vocational education and training (VAT) or baccalaureate. This implies an educational need to level up these backgrounds, together with a more student-centred, active learning. As a possible practical remedy, an approach of independent learning before the class was implemented, as in a flipped classroom. To this end, students were requested to study the topic scheduled for the next class independently as an out-of-class activity or 'homework', by using sources suggested (handbooks and web pages). At first, this task was not monitored. In a second phase, the task was monitored by a handwritten summary delivered before the class. A questionnaire survey showed that this type of homework was perceived as fostering a better understanding of theory in class and a more appealing class, but only if it was controlled as described. In addition, some differences surfaced depending on a student's educational background (VAT vs. baccalaureate), but also in repeaters vs. non-repeaters. A quantitative comparison of final-exam marks and homework marks reveals a better performance by most students with sufficient homework, although with some limitations.