How should the instructors and learners deal with the use of L1 language in a L2 classroom?

1. Research question: (this should be formulated as a ‘question’, not a topic.)
How should the instructors and learners deal with the use of L1 language in a L2 classroom?

2. Research method: (e.g. quantitative and/or qualitative)
Both quantitative and qualitative

3. Data collection tools: (e.g. experiments, questionnaires, observations and/or interviews) + (how many?)
Questionnaires and interviews. I will try 40+ student participants from different levels in a preparatory year program, and 10+ instructors (Those that speak Arabic and non-Arabic speaking).

4. Statistical analyses applicable (if any):

4. Theoretical significance of the study:
Leading scholars in the field have debated this topic over the years and I would like to look at it from a Saudi Arabian context and specifically from one of the biggest universities in Saudi Arabia, King Saud University.

5. Practical significance of the study:
I work in Saudi Arabia and as an EFL instructor; the institute administrations discourage the instructors of using the L1 in the L2 classroom. I have taught lower level students and I was forced to resort of using the L1 in the classroom sometimes but I try not to make it a habit. This study will give my self and the institution an idea of what both the instructors and learners think of using the L1 in a L2 classroom.

6. Selected up-to-date bibliography (at least 5 books and/or journal articles relevant to your research question):

Here are some books and articles I would like to use but it could also change:
Al-Shidhani “Teachers’ Beliefs about Using Arabic in the English Classroom”
Cook’s ‘using the 1st language in the classroom’
Cook’s ‘2nd language learning and language teaching’
Krashen’s ‘Principles & practice in 2nd language acquisition’
Harmer’s ‘The practice of English language teaching’