Based on participant observation and recording, my master's thesis studies differences in the behaviour of pupils during lessons, extended school days and school trips, respectively. The focus was on the behaviour of a class as a whole, individual pupils' responses, interaction between the teachers and the pupils, as well as among the pupils themselves. I was interested in all types of behaviour, particularly the outstanding ones and those that disrupted or had a negative effect on communication, interaction and group dynamics in the observed class. I also paid attention to the types of conducting the class, the teachers’ responses and the pupils' responses to her. The theoretical part presents the laws, school goals and school contexts, describing the course of lessons, differences between lessons, school trips in the morning and extended stay, respectively. Presented are the problems that the elementary school teacher encounters during lessons and trips, as well as the problems that the extended stay teacher is faced with, ending with a comparison between the contexts. This is followed by a chapter on understanding the behaviour and the factors that affect it. After I wrote about outstanding behaviour, where I presented a variety of classifications, reasons and factors, leading to disruptive behaviour. Lastly I described the types of classroom conduct and discipline. The empirical part presents a research that I carried out by observing the second class of elementary school. I observed the behaviour of pupils and their responses to the teachers' warnings, directed at their outstanding behaviour. I found out that pupils are very restless and they get bored soon. They often talk to each other, do not obey the rules and decline school work. Among other factors, such behaviour is often triggered by either other pupils, when a pupil would like to draw their attention, or when they think that they can do what others are doing. Teachers usually try to stop such behaviour with warnings and searching for reasons behind it. Pupils generally obey the warning, however, it often happens that they repeat the behaviour after a while. Most of the outstanding behaviour occurs during the second and fourth lessons, and least during the first lesson. The most of the disruptive behaviour occurs during trips and the least during extended stay. I compared my observations with the data sourced with interviews that I had conducted with both the teachers of the class, and some of the observed pupils. From their answers I found out that they don’t even know exactly when their behaviour is standing out and which behaviour is different from their expected behaviour by the teacher. They are acting like that because they are bored or they are entertaining themselves and schoolmates with it.