The most important thing in evaluating for relevance to your specific research project is to be clear on what your research question is as follows.
For example, your topic is learning disorders and your research question is, "What are some common learning disorders in elementary school-aged children?"
The following articles are probably too specific and too narrow to be relevant
Even so, the following articles would be too broad for that question.
However, if your topic learning disorders and your research question is, "What affects the comorbidity (co-occurrence) of different kinds of learning disabilities, and does having family members with more than one type of learning disability affect one's risk of having learning disabilities (and if so, how)?" then Comorbidity of Learning Disorders: Prevalence and Familiar Transmission would be of the right scope.
If you are looking for the most recent and up-to-date research on treating Alzheimer's disease, a research article from 20 years ago will not be appropriate and relevant.
For many of your research projects, you will be looking for recent materials, but some fields change faster than others.
This often happens at the beginning of working on an assignment, and most often the real problem is a lack of clarity about the research topic and question. For tips on choosing and narrowing a topic, visit Getting Started with Research or come talk to a librarian.