Do we have a TV?

Tonight as we read our bedtime stories, Sophie chose a book that was way beyond her level of comprehension. It was a guidebook for Spain, so I mostly just talked to her about the pictures. One picture in it was of a man watching TV. I asked Sophie, "Do we have a TV?" I figured she wouldn't understand since she's never seen our TV on except when she accidentally fiddles with the remote control and the screen lights up. We've been very strict about the no TV rule. Apparently, that's not enough for her to understand that the box in the corner is a TV because she turned around and pointed to it without much hesitation. I guess my next question should have been, "Do you know what a TV does?" I wonder how she's figured that out?