Researchers often use two-way mirrors to unobtrusively observe the interactions of animals or children.

He observed unobtrusively, because if he were seen, a dozen people would assault him with endless questions about a thousand little decisions-and he had enough on his mind.

Janeway tried to observe unobtrusively as the three of them made their way to sickbay.

She was level with them now, though shadowed from their notice and she could observe unobtrusively.

There was no need for complex or subtle spy apparatus; he simply observed unobtrusively.

Invited to look in on Sophie's play, I met the pair at the front door and nestled into a rocking chair from which to observe unobtrusively.

As I said before, Minstrels observe unobtrusively.

From the sidelines, the show's dance captain, Bill Burns, unobtrusively observed Mr. Bocca.

B'Elanna slid out of her chair, onto her knees, so she could observe unobtrusively without being observed.

An example would be to unobtrusively observe children on a playground (with a videocamera, perhaps) and record the number and types of aggressive actions displayed.