Explain, like analyze, often points in the direction of cause-effect or process reasoning. But explaining isn't always limited to analysis. Like discuss, explain sometimes appears in a test question when the teacher is asking you to write everything you know about a concept or when the teacher is focusing on a specific set of relationships. Treat explain, then, as a key word that calls for more exploration of the rest of the question to see if there is additional focus elsewhere in the question.
Writing tip: Because explaining can include any of the strategies noted for analyzing, defining, or comparing, be prepared to use a combination of techniques as well as transitional devices to create coherence in these responses. And because explaining leads toward longer responses, be sure to make a list of key points to include before you begin these responses; check your list for completeness of your response at the end of the test time.
Substitute key words: tell how, discuss