Little Dancers

[heslopian]

The sunlight pierces the window, Reminds me of a Shakespeare line: "What light through yonder breaks", except your line is more violent
lines of yellow split the room. Good metaphor for several sunbeams.
Here they are, they fill the air, How can they fill the air if they're also splitting the room?
specks of whiteness migrating about. What are these "specks of whiteness", exactly? Are they the sunbeams or air motes? If the latter then I guess my note on L3 is void. Also, is "about" needed?

They fade into view, taking the stage,
dancing, twirling, flipping, turning,
up and down, about and around. I like the dancing comparison, though I'm still unsure whether you mean sunbeams or air motes. Due to my interpretation of the evidence thus fair I'll henceforth assume that you mean the latter.

There seems a method to their madness, You haven't really implied that the motes' "method" is haphazard or "mad" before; on the contrary, you've compared them to professional dancers; so this line feels redundant. It's also cliche, so I'd recommend deleting it and adding "there seems" to L2 of this verse.
a music to their moves,
a story to be told.

Before I blink, they cross into the shadows,
lost forever but still dancing, Good line.
replaced by another but still spinning,
not in my view but still in my room,
the story still unfolds.

A neat and descriptive poem which makes luminous a very simple idea. My above critique is all JMHO, of course. Thank you for the read.