Much research has been conducted explaining CLT's emergence as an alternative to the traditional methods of teaching language. Its extreme popularity in the U.S. is well known, but it has spread all over the world, which can be interpreted as a sign of its effectiveness. However, its application in other countries has yet to be studied sufficiently.
In your research proposal, you can study the effectiveness of CLT with different age groups. You can include psychological aspects of the language acquisition. For example, young children may be very shy, while pensioners may be eager to participate in conversation, because their self-confidence is higher. Your proposal can be aimed at comparing various CLT strategies and their effectiveness with a particular audience.
Conduct your own experiment using two different groups of people for testing language proficiency and competence. Choose one group of learners who were taught using CLT approach, and another group of learners who studied the same language with traditional methods. In your research proposal, you can indicate a testing system of language proficiency and how it is possible to apply your testing system to these groups during your research. Also, expected outcomes must be pointed out in your proposal.
CLT has been widely criticized by scholars. Unfortunately, there are many negative outcomes of this approach, indeed. Its strong point is it gives a learner feeling of self-confidence while speaking, but it is recognized that CLT students do not have strong writing skills. It is good for tourists who will be happy to talk to the locals in their native language during their trip abroad, but it is inappropriate for those who must deal with documents and desire to find a good job. Your proposal can be dedicated to the problematic outcomes of CLT.