Brooke's band

I visited Brooke's class for just a minute today.  She saw me walk in and she came up to me with one of her friends, Alayna.  Brooke said, 'Mom, we're working on our band.  Alayna, what are you going to do?'  Alayna, 'ahhhh'.  Brooke reminds her, 'you're going to play the keyboard.'  Another little girl passes by and Brooke stops her and asks, 'and do you remember what you're doing?'  The girl says, 'ahhhh'.  Brooke answers, her own question, 'whistle.  You're the whistler.'