I have discovered the truth about my older sister Eva. It wasn't easy to understand at first. Then, when I uncovered the truth, it all made sense.

It began when Eva started talking on her cell phone constantly. I mean, every minute of the day. She was on the phone in the morning, when she came home from school, before and after dinner, and right before bedtime. I don't attend her sports practices, but I thought that she was probably on her phone then, too. I bet Eva talked on her cell phone in her sleep!

Eva also became very secretive. If she was talking on her cell and someone came into the room, Eva disappeared behind a closed door. Or she dropped her voice to a whisper. Sometimes she simply hung up and glared at whoever interrupted her.

And Eva was moody. Sometimes she'd burst into song, skip down the stairs, or rush to hug me and tell me that I was the best younger sister in the world. Then, for absolutely no reason, she'd burst into tears and shriek, "You don't get it! You'll never get it! It's hopeless!"

Mom and Dad shrugged and called it typical teenage behavior. My little brother, Alex, didn't seem to notice anything at all. Isabel, Eva's twin, seemed irritated, not worried. She rolled her eyes and made sarcastic remarks. It seemed like I was the only one who was disturbed by Eva's strange new behavior. I didn't know what to think. Was she skipping school, smoking cigarettes, or . . . what? But that didn't make sense. Eva loves sports and everything healthy. She's also an A student. So why was she acting so weird? If she had nothing to hide, why was she so secretive? And why was she ALWAYS on the phone? Then I discovered the truth. I'd seen it in movies and on TV, but now it was happening in my own home. It was totally obvious once I saw it. My sister Eva was in love! That's why she was so moody. That's why she was on the phone all the time. That's why she was acting so mysterious.

No one else in the family seems to have a clue. Not even Isabel. I'm the only one who knows. Right now, I'm keeping it secret. Uh-oh. I have to go. It's almost time to catch the school bus.