Today is the day: I'm selling my daughter's first bicycle, complete with training wheels and helmet. She outgrew the 16-inch Barbie bike a long time ago, but it's been hard for me to part with yet another tangible reminder of her littler years -- even though she's pedaled far beyond those days. So I've filled out the card that will go on our for-sale sign at work. Gosh, it's hard to let go. If that isn't enough, she informed me yesterday that it's time to clean up the bulletin board in her room. I truly didn't know what she was talking about. But then I went in and took a good long look. It is layered with pre-kindergarten art projects and mementos of toddlerhood, pictures of her when she was a baby. It's all little-kid stuff, she told me in an exasperated tone, "and I'm going into fifth grade.'' Oh how sobering to realize that the board in her room was really more for me than it was for her. So tonight, down comes the baby and up goes the tween. Where is the time going?