Fun with wireless

I’m using WiFi for my Internet connection. From the access point, the signal has to go through two floors and across the house to get to my home office. I was able to get a decent signal (two bars) by strategically placing the laptop. Today I discovered something new. When I close the door the the room, the signal strength goes up to three bars. The signal must have an easier time propagating through the wood of the door and down through the house than over the air!