In my research, I have four classes of students, and these classes have been divided into four groups. The students in these groups are pursuing their studies in four different academic disciplines, and the university has placed them into these classes as a requirement, without my involvement in the selection process (as the researcher). The instructor of the classes is tasked with teaching them reading skills for three months to assess how four independent variables affect dependent variables (one of which is reading comprehension skill). The critical question I'm facing is the choice of reading materials for teaching the reading skills. I'm considering whether to use materials at an intermediate, upper-intermediate, advanced, or another level. The challenge is whether it's reasonable to select a single level of materials for students who likely have varying levels of language proficiency and reading skills (heterogeneous students/heterogeneous groups). I'm also pondering whether it might be more justifiable to use texts of different levels to accommodate individuals with different language proficiency and reading skill levels.
Would you please provide me with an academic explanation, suggestion, and justification to solve this challenge?
You can subtly homogenize groups. Perform the same training for all individuals in the groups, but exclude outliers (people at very high and low skill levels) from the statistical calculations.
Your task as a lecturer is to teach a certain reading skill within three months. The aim is to find out how four independent variables affect four dependent variables, one of which is obviously reading comprehension skills - so far so good.
But the overall research design or study concept seems to be much more complex. Thus, it remains largely unclear how dependent and independent variables are defined, operationalised and how they should be correlated in the end. In view of this, it is not entirely trivial to answer your question, as this in turn could have consequences and implications for the overall research question.
Basically, the question is whether there is a kind of graded framework for language competences in your specific field. An international example would be the "Common European Framework of Reference for Languages: Learning, Teaching, Assessment" (https://www.coe.int/en/web/common-european-framework-reference-languages). This differentiates 'language competence' into three levels: elementary (A), independent (B) and competent (C) language use. Each level is further differentiated into two competence levels, with four skills being recorded for each level, namely: reading comprehension, listening comprehension, writing and speaking.
With reference to this, each of these linguistic competence levels and competence levels can be assigned specific teaching/learning material. Whether and to what extent school material is helpful here depends on several factors. This would require a separate discussion.
Keep in mind, if you use different reading levels for each group, then it will be difficult to compare comprehension because you have manipulated an important variable. While the other three variables are not listed, if reading comprehension is a variable, four different manipulations will not allow a fair comparison because they have four different conditions; the materials, not the teaching might be the omitted variables.