Search for your topic by Keyword.
Example: Biology Study and Teaching Elementary
Then: Once you locate a "good" choice in the results list, display the complete entry, and look at the Subject Headings.
When searching SLUth - Search Plus, try using the following as SUBJECTS, along with your topic and some related keywords for it.
Teaching Methods in SUBJECT OR Science--Study & Teaching in SUBJECT
Elementary Education in SUBJECT
Your topic plus related terms -- Example: Microbiology or microbes or microorganism* or bacteria or fung* in All Fields
Select just the Education ebooks. Next do a search for
molecular biology in All Text Fields
elementary students in All Text Fields
LIMIT by SUBJECT in the left-hand column to science--study and teaching (elementary)--united states
The results are shown below.