When evaluating sources, you want to consider the following:
When considering the validity of the source, ask yourself the following questions:

Adapted from TUS Library, (n.d.). 5 W's of information evaluation. Critically Evaluating Journal Papers. https://tus.libguides.com/friendly.php?s=criticallyevaluatingjournalpapers/5wsofinformationevaluation.
Popular sources are not "bad" and Scholarly sources are not "good". It is a matter of context and what source and source type is appropriate for your research. You must read the source, investigate the validity, and decide whether that particular source addresses your research question.
Consider potential bias and perspective, in addition to validity and relevance, when evaluating sources. Be open to new perspectives, and always view sources -- no matter who wrote them -- with an attitude of informed skepticism and awareness of potential bias. In addition, be open to voices that may not be traditionally thought of as "expert" or "authoritative", especially marginalized voices that may be underrepresented in traditional publishing processes.
Here are some questions to consider as you think about bias/perspective, particularly when looking at sources related to your teaching practice:
Adapted from Relay Graduate School of Education Literacy, (n.d.) Evaluating sources. Information Literacy LibGuide.