Art? What is art?

I'm pretty mad at my art teacher right now, and have been for awhile. A couple of my friends and I asked if we could decorate a cake as one of our free assignments. She said, no, other people had asked and it just wasn't something she would allow. She also said that if we wanted to bring her a cake anyway, she wouldn't say no to eating it. We were pretty angry at that comment.
So now is when I ask you, wonderful people of Mibba,
Would you consider cake decorating an art?

What's more is that several sculptures have appeared around the school, like a desk covered in chewed bubble come, and a dozen paper stop signs. All I could think was how could she allow that but not a cake?