To circle back means to return to a topic, task, or conversation after dealing with other matters first. When your teacher says, “Let's circle back to that question after we finish this example,” she plans to discuss it again once the current lesson is complete.

The phrase comes from the image of making a circle: you move away from a point but eventually return to where you started. In meetings, people often say, “I'll circle back to you on that,” when they need time to gather information or think something through before giving a proper answer.

Sometimes circling back happens quickly, like when you're explaining a story to a friend and realize you skipped an important detail: “Wait, let me circle back to what happened at lunch.” Other times it takes longer, like a class that studies ancient Rome in September and then circles back to Roman engineering when learning about aqueducts in March.

The phrase can also carry a slightly negative meaning in workplace settings, where “let's circle back on that” sometimes becomes a polite way of postponing a difficult conversation indefinitely. But in most cases, it simply means “we'll return to this topic when the time is right.”