Ever-increasing world population requires efficient food production and extensive urbanization. Hence, annual increase in implementation of nitrogen fertilizers which increases agricultural yield, but also increases water pollution. This thesis gives an overview and an assessment of water quality of Drava River, based on the analysis of water physico-chemical parameters according to the national laws and regulations. Water samples were collected monthly over a period of 13 years (2004 – 2017). Analysed parameters were, among others, pH, chemical oxygen demand (COD-Mn), five-day biochemical oxygen demand \( BOD_{5}\)), nitrogen (nitrates, nitrites, total nitrogen) and phosphorus compounds (orthophosphates, total phosphorus). The obtained results indicate a water quality status between good and very good, depending on the parameter and year. Regardless, continuous monitoring of water quality is necessary in order to ensure adequate implementation of measures for water quality protection. Also, the thesis contains a methodical part regarding class unit “Water” for the 7th grade of elementary school. The methodical part contains written preparation for the class, supplement 1, experimental part, worksheet and homework sheet. The frontal type of class is planned, pupil group work and ending with joint review of the lesson with the help of the worksheet.