A thorough, yet concise explanation of Prime and Composite numbers. Also it’s development throughout elementary school, as laid out in the Common Core State Standards. It should also include an examination of how the topic is handled in a particular elementary curriculum series (e.g. Engaged NY) and any challenges that the curriculum creates. (e.g computational or conceptual complexity).
In addition select a single problem/activity that allows elementary students to interact with the important ideas of the topic and explain why you chose it (discuss the content understanding goals of the activity, how the activity addresses them, misconceptions that it might address/draw out, etc.).