One of the methods applied in linguistic and didactic research is the quantitative or statistical one. The importance of statistical data from a didactic perspective is explained by the requirement that the teaching process of the compartmental units of the foreign language be carried out in the descending order of their degrees of occurrence. The influence of the mother tongue is the main cause of mistakes in the process of acquiring the foreign language. In some cases, the impact of another foreign language, learned previously or concurrently as a basic language, German being the second, may be the cause of the respective mistakes. In this context, the paper deals with didactic forecasting in the teaching and learning of compound consonantal monophonemic units of English and German.