When and While with Past Tenses

While + continuous; when + simple action.

Examples

• While I was cooking, he called.
• When I arrived, it was raining.

Key rules

• Use while with a longer continuous action (While I was cooking)
• Use when with a short action or a point in time
• A shorter action can interrupt a longer one: I was reading when he called
• Use a comma if the time clause comes first

Common mistakes

• While I cooked, he was calling → While I was cooking, he called
• When I was arriving → When I arrived