Observability is the ability to mark, remember and reproduce as much detail as possible from the perceived object. It is generally believed that better or weaker observability is related only to visual information, but a great deal of detail that can be discerned or left unnoticed also provides the hearing. For example, in a sounded musical work one listener can mark specifics of harmony, of the texture, of the structure, expressive moves in the inner voices, different techniques used by the performer. In the same musical work, another listener can only discern the soprano melody and, in some cases, even not remembering it. This comparison gives us an opportunity to make conclusion about the usefulness of observability in terms of the richness and completeness of perception. The usefulness of observability, however, is not limited to the fullness of the aesthetic pleasure of perceiving a work of art. It is related to the success of each task, as it provides the one who solves the task with more voluminous, more accurate and more detailed information. Some people have a wide range of observability, others are not particularly good. In all cases, however, this valuable human ability is subject to development and improvement. Naturally, the great benefit of having good observability and the fact that it can be improved shows that care should be taken to develop observability at school. Conditions for the development of observability should be created in the textbooks, providing a sufficient number of tasks useful in this respect. In the electronic textbook on music for the 4th grade of the general education school in Bulgaria, which I will analyze in this report, there are several groups of tasks, which, besides their focus on mastering the learning information, have a direct relation to the development of observability. In one of these groups of tasks must be corrected errors in written text. Observability, in this case manifested as the ability to quickly and accurately detect where, what and how many mistakes are made, without any other tooltips, along with the well-learned knowledge is essential to solving these tasks. Other electronic resources are tasks for arranging in groups terms, musical instruments, signs used in the musical score. Observability here is needed to identify timely the elements belonging to a particular group or those, that do not belong to any of available groups. The arrangement of elements in a table - another group of electronic resources in the textbook - is related to quick orientation in the table compilation logic, the comparison of the items whose places are to be searched, by two types of attributes and finding the exact location of each element according to the specific for it ratio of these two types of attributes. In the interest of better development of observability and assimilation of knowledge by pupils in some of the tables in individual cells must be placed two or more elements, and other cells to remain blank. A specific group is formed by the tasks of selecting more than one correct answer. There are assertions listed in these tasks, among which the students must choose the correct ones. Unlike tasks with a single exact answer, the number of correct answers here is not known in advance. It is not known whether or not there is a precise answer, and also whether all the answers will prove to be correct. In these cases, observability, the ability to assess after extracting the largest possible number of characteristics, is definitely important for a successful decision.
Analysis of Ligeti’s Atmosphères by Means of Computational and Symbolic Resources
