This study investigates three models of content-based instruction in teaching concepts and terms of natural sciences in order to increase the efficiency of teaching these kinds of concepts in realization and to prove that the content-based instruction is a teaching strategy that helps students understand concepts of natural sciences. Content-based education is considered effective not only in acquiring the skills of language, but also grasping and mastering the content knowledge of academic subjects that are required for students' achievements in learning the terms related to natural sciences. In analysis of three models of content-based instruction, the Adjunct Model was explained and mentioned to be quite reliable for the teaching content of any subject along with foreign language methods and techniques. It has been proved to be convenient for both content and language teaching through pedagogical experiment. "Participants" were undergraduate students from the Engineering and Natural Sciences Faculty of a university at intermediate level. The achievement test was applied to 48 students who were English and Turkish speaking students as foreign languages. Two working groups as experimental and control were formed by language teachers. The collected data was analyzed. The results, mentioned in experiment part, and conclusion show that concepts or terms of natural sciences could be taught efficiently through content-based teaching in schools and universities.