Actually, it's Phil trying to unwind the kids by reading to them; it doesn't quite take but it's more than Elly ever did.
Panel 1: We see Phil, who's sitting on a bed with Mike and Lizzie, holding a copy of Yuletide Classics; he says "'Twas the night before Christmas and all 'round the tree...." to which Mike responds "That's not how it goes!!"
Panel 2: He then says "'Twas the night before Christmas and all 'round the ring, the fans were betting on which guy would win."; Muppet-Mouth Mike smiles and says "No!!" while Lizzie giggles.
Panel 3: Mike screams in delight as Phil says "'Twas the night before Christmas and all through the street, the vampire was looking for something to eat."
Panel 4: They resume the horseplay that we ended the week with.
Panel 5: We shift focus to the kitchen; John, who's leaning over Elly's shoulder as she reads the newspaper, asks where her brother is. She tells him "Upstairs, reading the kids to sleep."
Summary: As I said, his attempt to get them to sleep doesn't take because he's being silly; still, he's paid them more attention and given them less grief for being kids than Elly is capable of.