The level of mathematical knowledge of secondary school students in Central Europe is not satisfactory and is declining, or at least stagnating in most European countries. If we want to improve the mathematical skills of our students, it is essential that teachers explain mathematical topics properly and in an interesting way. On the other hand, pupils also have to actively exercise these topics and thus enhance their mathematical skills. The project has two main goals: The first one aims to enhance mathematical competencies of students in secondary schools and in the latter years of primary school education by incorporating new, interesting and unconventional interactive exercises into mathematics. The second goal targets improving the English skills of teachers and pupils in mathematics by creating all project outcomes in the English language as well as versions in the local languages of project partners. During the project, we are going to create a web portal for exercising the whole range of secondary school mathematical topics. This portal will consist of the following essential parts: • A database of 4,000 questions and exercises. • An online test generator for students – a student selects a topic, a subtopic and a difficulty level that he wishes to complete and the generator will deliver an interactive test according to their selection. The generator will provide tests for all common hardware platforms (computers, tablets and mobile phones) running the most popular operating systems. • A Web application for user defined tests – this tool is dedicated mainly for teachers to generate customized tests. The teacher will be able to select questions from the database and the application will generate interactive tests with instant evaluations and corrections automatically. This test can be used on an interactive whiteboard or computer. Another option is to generate a hard copy non-interactive test. • 150 interactive training games – materials focused on the training of certain mathematical topics, e.g., expressions simplifying or training in the basic values of trigonometric functions. • Each question, test and game will be available in four languages (English, Czech, Polish, Slovak).All interactive HTML tests, interactive PDF tests and training games will have a unified user interface taking into account specifics of the target hardware platforms. After passing a test, the students will receive an immediate evaluation, score, success ratio and correct answers. Some tests will also contain help, e.g., definitions, or proper solution procedures. The tests will be accompanied by many figures with a goal to strengthen understanding of the geometric meanings of trained topics. We will also focus on other activities such as: • Summer schools for students • Shadowing teachers of mathematics • English language training specific to mathematics • Pilot use of project outcomes. Materials will be tested and verified on a sample of 900 students. • Propagation and dissemination. We assume 35, 000 visitors of this newly created web portal during the project and even more after the end of the project. Google Analytics will be used as a measuring tool. The project implementation team consists of partners from three countries. A team from the Czech Republic is composed of the project coordinator - VSB-Technical University of Ostrava and the two partner secondary schools – Wichterlovo Gymnázium and Gymnázium, Ostrava-Hrabůvka. Two other partners are from Slovakia - Gymnázium (Varšavská cesta, Žilina) and Gymnázium Antona Bernoláka, Námestovo. The last two secondary schools are from Poland - Liceum Ogólnokształcące and Technikum that belong to the association of schools Zespół Szkół Ogólnokształcących w Lipnicy Wielkiej.We expect that all outcomes and activities of the project will have a direct impact on: • Enhancing the mathematical skills of students in secondary schools - acquisition and consolidation of mathematical knowledge and skills. • The refreshing of teaching and learning processes through interesting and unconventional interactive training materials. • Increasing interest in mathematics, even among students with low interest in mathematics, via computer -based practices. • Improve the English-language skills of teachers and students in mathematics. Teachers will be able to use a number of educational materials in English, which is offered as part of open education. Students will have broader opportunities for participation in international meetings, summer schools, workshops and other events within the EU.The direct impact of outputs and activities of the project will be felt primarily in those countries participating in the project. Thanks to English-language versions of the projects results, they will be ready for use in a wider, international scale. Moreover, this project will synergistically complement the already approved project Horizon2020, called STEM4you (th).