Time series consists of series of chronologically arranged phenomena that differ in time. The goal of this research is to make an analysis of the theoretical part of the time series and all of its important components, such as arithmetic medium, from which one can read for example average scores, as well as chain and base indexes, from which one can read variations of grades, for example at which rate has certain grade been reduced or increased. Theoretical time series elaboration is necessary and has a purpose to serve as a basis for further analysis of concrete examples from practice, such as student surveys. Student surveys have been regularly conducted since summer semester of academic year 2011./12. using electronic means at the College for Management in Tourism and Informatics in Virovitica. Based on the grades awarded from students to teachers, each teacher's progress is being analyzed in order to improve the quality level of the teaching process. Student surveys are being conducted upon finalization of each summer and winter semester. Students are grading the performance of each teacher included in teaching process in their respective semester by the area of grading. The analysis has been carried out using MS Excel tool. The analysis particularly focuses on the area of teachers' appraisal. Each teacher, according to the academic year of the survey, gets calculated average scores, from which indexes can be calculated (chain and bases), and compared to see whether the ratings of a particular teacher have decreased or increased, and in which academic year semester teacher had best or worst evaluation results. All teacher's grades are presented and jointly analyzed at the end of this analysis.