While we were in the bookstore this evening, Alyssa saw the 20% off sign and asked me what does it mean. So I used the fairy book that she wants to buy as an example to explain the concept, instead of $5, she only has to pay $4 with the discount. She thought about it for few seconds, and responded: "Wow, that's cool. I am going to wait when they have a 100% off sale!"
Well, good luck my silly girl.