The aim of this study is to analyze the sentence patterns of Turkish-German bilingual students based on a three-way classification (insertion, alternation, congruent lexicalization) and to find out whether there is a Matrix Language that determines the grammatical structure of the sentences, which include code-switching, or not (Myers-Scotton, 1993). 5-month-long WhatsApp group conversations ... [Show full abstract] among six students and their Turkish language teacher Salih Bektaş (45), who is also a Turkish-German bilingual, are analyzed. All of the students are from the fourth generation of the Turks living in Germany, and they were all born in Germany and are still living there. On the contrary to the allegations of the the Matrix Language-Frame Model, the hypothesis is that there is no Matrix Language that governs code-switching, rather code-switching is the outcome of the convergence of two languages. This converged system does not violate either of the grammatical systems of the languages involved in code-switching. The outcome is that, the structure of the sentence and the way that code-switching occurs, depends on the environment and the interlocutor, and there is no language that dominates code-switching.