Our contribution is devoted to study the ability of future chemistry teachers to organise pupils’ observation of chemical phenomena. In this article measuring of multi-level means is described, which should denote a readiness of probands to perform an observation during carrying out chemical experiment. It is based on the assumption that well-prepared observers are able to work actively and to propose alternative solutions, because of their deep understanding of a procedure. In next part of this article the results of a research carried out at Faculty of Natural Sciences in Bratislava are analysed. The research was also aimed to detect if students are prepared to perform chemical experiments without a risk that they will be confused by a procedure or different course of experiment as they had expected.