Toward the end of chapter 1 in Little Nightmares you will enter a room with a TV among other items. After spending some time trying to turn on the TV and climbing the objects around you, you might be wondering what you need to do here. We have an answer.
First, make sure that the gear on the floor is repositioned near the door, preferably to the left where it's dark. Then, you need to turn on the TV.
To turn on the TV, you need to push against the TV where the button is. Using action buttons doesn't work for some reason.
Once the TV comes on, the long-armed monster will come rushing into the room. You need to wait on the other side of the door where you've (hopefully) moved the gear.
Pick up the gear, and wait for the monster to walk to the TV and put his ear against it. At this point you can run without him hearing you.
Your goal is to backtrack through the Library to the spot where the gear can be placed. Push it in and turn it to reveal a piano that you can jump on.
Of course, you'll need to do this while the monster comes rushing for you, so be quick and preferably stand on the far end of the piano to avoid being grabbed.