said Robin.“Castles in the air. Our project that we have one week to do. In case you’ve forgotten.”“I haven’t forgotten.” Robin’s eyes felt like they were stuck together. She had been awake most of the night, tossing and turning, worrying about Kim’s stupid birthday party. How was she ever going to get the nerve to tell Kim she wasn’t going?“It’s an expression,” said Kim. “Mom’s heard of it.”Robin looked at her blankly.“Castles in the air. Oh, forget it.” Kim slumped back in her seat.“Sorry.” Robin pulled her mind away from the party to easier ground. Kim always got in a flap about projects, and they always came up with something good at the end. “I’m listening now. Honestly.”Kim dug a piece of paper out of her pocket. “I wrote it down because I wasn’t really sure if I got it.” She frowned. “It means something that’s not realistic.”“What?” said Robin.“Mom said it’s like when you have dreams, but they don’t have a chance of working out because they’re not realistic.