This paper highlighted on effectiveness of the student perception of applying this kind of mechanism (code-switching and code-mixing) in the classroom. Many research claims that teaching in classroom using these approaches makes the lesson more clear than using one language for the student regarding the teaching but at the same time its disadvantages more than its advantages, and also in the speech case when using the approach will clearly give an unsatisfied amount of results, and might cause a “terminological confusion” of the sentence during the speech whereas it has an unclear effectiveness on the student language vocabulary and perception during the time. The data of this research collected form five universities in Indonesia, and interviewing five students of every year in every university (100). The results and the outcome of this research were more than positive, switching and mixing in the classroom is considered in the classroom for about nearly 85%, students faces an unconscious threat for their language and speech fluency, not to mention the lake of vocabularies that encountered of applying this technique as a teaching mechanism in the classroom. This research is a combination of sociolinguistics and psycholinguistics mechanism studies the how and the why the act of “terminological confusion” happened.