I am looking for research or journal articles about adding alternative reading materials in math classes.
For a topic like this, I would recommend starting with an education-oriented database like ProQuest Education or ERIC. If there’s a specific grade level you’re interested in, you might also try Primary Search for elementary school grades, Middle Search Plus for middle school, or MAS Ultra for high school. In any of them, try a search like:
You can limit to just full text articles, or just scholarly articles, as well. The asterisks look for variants of words, so math* finds math, mathematics, mathematical, mathematician, etc.
If you aren’t finding what you need, try changing the keywords around. I’d also be glad to assist you further.