Research supervisor is easily distracted in meetings with me I don't think my research professor takes me seriously. I have noticed that in several of my meetings with my PI, he gets distracted very easily. 

Now I know of people my age who get distracted (in their 20s), but he insists it's something natural... and he's way older. For example at our last meeting, he was advising me on what I should do for the next part of my project, I was writing all that stuff down, and then he spaced off. I was looking through my notes to see if I understood everything correctly, and he stared up at the ceiling. Next, he asked me if I knew what the ceiling material consisted of. When I said I had no idea (I was trying to brush off the question because there are more important tasks at hand), he made me look it up on the spot. At the moment I thought he might have become bored, maybe there was an awkward silence, but now that I've been thinking about it more, this is not the first instance where this has occurred. He does this in front of my other classmates as well. 

Is he just joking around? Trying to lighten up the mood? Am I awkward? Am I not important? How do I address this to him?
Most people can concentrate better when they are still fresh, so my suggestion is try to schedule a meeting with him early in the morning, or as early as possible. Like the other answer has suggested, try to keep the meeting as compact as possible. Also, you might also have to try to keep him occupied on you so that he don't have any time to start thinking of something else. This can be done by keeping the discussion on. You have to learn to write while thinking and talking at the same time.