The Information Hiding Principle is a modularization technique aimed at increasing the productivity of software development and maintenance. The Hiding Information concept introduced by Parnas is recognized as one of the key software design principles. However, as the author said, implementing the Principle is harder than it looks. This paper aims to discover what students understand and how they implement, on their designs, the Information Hiding Principle. The research was conducted through a qualitative case study with thirteen Master's students in the domain of Software Design. Among the different concepts associated with understanding the Principle we could identify that some students adhere to the idea of dividing in order to hide, while others only care about hiding. Both of them without a successful implementation of the Principle. Few students have some idea about the Principle, however they do not get it all when implementing it. Furthermore, we can conclude that Parnas' statement remains until today.

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Operating Systems is a difficult subject to learn; however, little is known about these difficulties, as they have not been studied or determined by the relevant literature. The objective of this article is to specify the most difficult concepts for understanding the subject and misconceptions that students have regarding these concepts. The study was conducted through an online university over the course of an entire semester. The research data comes from the evaluations taken by nine students, which have been analyzed using qualitative methods. The most difficult concepts for students to understand include concurrent computing and the mechanisms to change the program that the processor is running (interrupts, context switches, system calls, etc.). Six misconceptions regarding these concepts have been identified, helping to determine the specific problems that need to be resolved.

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