Qualitative preparation of pre-service teachers remains an actual problem. Appropriate school preparation is important for studying at university. This is very actual for future natural science teachers because the candidates of very different knowledge and ability level enter Lithuanian (and not only) universities. Such condition is presupposed by Lithuanian (and not only) general secondary education system because all natural science subjects (physics, chemistry and biology) are compulsory up to the 10th form, and in the 11th -12th (3rd -4th gymnasium) classes, only one of all natural science subjects is compulsory, or an integrated natural science course. Besides, students taking into consideration their needs and inclinations can choose general or extended natural science – biology, chemistry or physics course. Five university scientist groups carrying out an international project “Developing Bridging Courses for Mathematics and Science Teacher Students/Bridge2Teach/” started solving this problem. The aim of the project is to create, test and develop the bridging courses designed for the preparation of mathematics and natural science teachers. In this way, it is sought to do away with the gap between what was learnt at school, and what is necessary starting the studies at university. In Siauliai university, for the pre-srvice Integrated natural science teacher knowledge consolidation, 12 ECTS credits course Holistic natural phenomena conception is foreseen in the programme, by which, filling the gaps in natural science knowledge, it is sought to form entire, holistic world cognition, to motivate students for deeper natural science understanding and interpretation, to awaken willingness to explore. The studies of this course are organised so that every student should have a possibility to acquire lacking natural science knowledge, to extend it, and to actualise. All Siauliai university study programme Integrated natural science pedagogy students, having participated in the survey, unanimously pointed out that having started studies at university, at a different level they felt gaps in natural science and mathematics knowledge and abilities. As the main solution way of such a problem, the students indicated bridging course organisation for the first course students, accentuating that for successful studies at university, general and even extended mastering of the school course is necessary. Having generalised teachers’ who participated in the expert survey answers about bridging courses for students in natural science and mathematics and their need, one can claim that students, who enter higher education, have school knowledge gaps, which could be at least partly fulfilled by properly prepared and realised bridging courses. Lecturers experts claim that bridging course content depends on the chosen study direction (even on the study programme) because, basically, the necessary knowledge for the students having chosen different study programmes differs. They accentuate that such course demand for every future student should be individual; they note that to include such course in study programmes is problematic. Keywords: bridging course, international project, mathematics course, science course, science education.