I would suggest that you do something like this with Jenny. In a private conference, happily list what you like to do with and for her. Then end with, “So you're not allowed to complain in this classroom, OK?”
To dig deeper, it's interesting to consider what children think about their own complaining. To investigate this, I asked several children why they whine. Here are their responses:
Donald, why are you complaining?
What are you doing?
Telling you he's pestering me.
Your voice sounds like it's complaining.
It isn't. It's Donald.
Emily, sometimes you complain, and it's very annoying. Do you know why you complain so much?
I might be sick.
Every time you complain, do you feel sick?
You were complaining a few minutes ago about not wanting to go outside to play. Were you feeling sick?
Then why were you complaining?
I might be sick.
When I'm complaining.
These dialogues demonstrate that young children may not know the meaning of the word complaining, and that they may not recognize it as that when they do it.
Here's another dialogue I had with a preschooler:
You're complaining. Do you know what complaining is?
Why are you fussing and fussing and fussing?
I want the bike.
Fussing is not the way to get what you want.
I don't fuss when I want something.
What do you do? What's the right thing to do when you want something?
You could grab it. You could scratch her face.
But would that be the right way to say you want a turn?
No. You might go in time out.
What would be a better way to tell a grown up that you want something?
I could complain.
This illustrates that young children's logic is quite remarkable and can be quite peculiar. Their train of thought is not always logical.
Considering that all of these dialogues reveal much about how young children think, you can tape-record a small collection of Jenny's complaining and whining behavior, then play it privately for her. The ensuing conversation should make it clear that this is complaining and fussing and whining.