The main purpose of the work is to present a successful implementation of CLIL method in Mathematics lessons in elementary schools. Nowadays at all types of schools (elementary schools, high schools and universities) all over the world every school subject tends to be taught in a foreign language. In 2003, a document called Action plan for Language learning and linguistic diversity was approved by the European Union. Its purpose was to enable the acquisition of at least two foreign languages for all European citizens. The integration of content and language skills is a part of the plan. Within the school educational programs it is possible to choose CLIL (Content and language integrated learning) method. This method is an upward trend in contemporary education system. Teaching Maths in a foreign language requires some changes in current teaching methods, so the importance of the IT technologies is also mentioned. The work studies the impact of the CLIL method in teaching Mathematics and possible changes of the classroom climate and shows the results of the research focused on this method.