In secondary sources, authors analyze and interpret primary source materials.
Secondary sources can be scholarly or popular. Scholarly sources (sometimes called "academic" or "peer-reviewed" sources) are written by and for experts and typically include bibliographies and citations. Popular sources are written for a general, non-expert audience and can be authored by anyone.
Tertiary sources are excellent starting points! They consist of information synthesized from primary and secondary sources. Examples include:
These resources give you succinct overviews of your topic, explain scholarly arguments, point out interesting questions, and refer you to especially key sources.
In order to provide context for your chosen items and inform your commentary, you should look for additional (outside of class readings) tertiary and secondary sources that explain the context for the example/artifact. You can find keywords and larger framing ideas in the course reading and then look them up in the library catalog and subject-specific databases, looking for scholarly articles and books/book chapters that help frame your commentary about your items.