The necessity for the project is closely related with the teaching of STEM subjects using C.L.I.L. over the last years when private secondary school KLASIKA teachers started using C.L.I.L. methodology in designing lessons in STEM subjects. In the beginning those were math lessons for grades 7,9 and 10 which were first planned and then taught to the students. At the same time math and economy teachers Tatjana Vinokurova and Svetlana Shibko-Shipkovska constantly improved their knowledge of the English language attending language courses in Riga and studying on-line as well as gained knowledge in C.L.I.L. methodology in STEM subjects, for e.g. "C.L.I.L. Essentials", "Future Classroom Scenarious" and others (mentioned above). The language support in the choice of language material was and still is provided by the English teacher Māra Kreicberga. Further on school KLASIKA participated in the International project VIA LIGHT to support children multilingualism, the economy teacher Svetlana Shibko-Shipkovska was one the project's coordinators. Later math teacher Tatjana Vinokurova entered the project "More Meaningful Math" (school KLASIKA is a partner in the project with five other European countries). Meanwhile more math lessons were designed using C.L.I.L. and presented to the students in the secondary school. The lesson plans, the experience gained through the planning and teaching STEM subjects using C.L.I.L. were shared in e-Twinning with partner schools in Belgium, Cyprus, Switzerland, Spain and Germany and discussions followed. In cooperation with the Agency of the Latvian Language workshops for the math teachers from other schools in Riga were designed and prepared (total amount of lessons - 36). The support in language methodology and classroom vocabulary was provided by the English teacher Māra Kreicberga. Lesson plans made and shared by other European Schools and offered in e-Twinning were used in KLASIKA STEM lessons applying C.L.I.L. Furthermore, to prepare for mobility, during the mobility and in the after mobility period math tasks, lesson plans, worksheets were designed and offered to the students of the international teams within the project "More Meaningful Math". The experience, knowledge and designed materials were all shared in e-Twinning. The school's methodological council having accessed the demand for high quality education and the importance of STEM subjects decided to make the use of CLIL methodology in STEM lessons a part of the school's study programme and school's development plan. To further develop the skills and gain more profound knowledge in using C.L.I.L. in STEM it was decided to use the mobility. The courses chosen fully meet the demand for C.L.I.L. methodology, language skills and providing the support of the English language material. To choose the teachers the following criteria were applied - experience in using C.L.I.L. in STEM subjects, knowledge of the English language, experience in project work, teaching STEM subjects, use of innovations, personal interest and motivation letters.The planned activity is mobility to further make teaching STEM subjects using C.L.I.L. a part of the school'sstudy programe and school's development plan, to improve the methodology in using C.L.I.L. and to improve the knowledge and skills of the English language. The experience and materials in methodology will be shared in e-Twinning, National press and internet medium, for.e.g. "skolotājs.lv", school KLASIKA website, through a workshop organized for the teachers from schools in Rīga, exchanged with the project "More Meaningful Math" partners. To sum up, in school KLASIKA STEM subjects will be taught using C.L.I.L. as a part of the study programme and relevant methodology further developed and improved and the students motivation raised accordingly resulting in quality education corresponding to European standards.