Novelty is exciting because it provides different ways of looking at the same subject. For instance, comparing The Three Little Pigs to The Real Story of the Three Little Pigs is usually stimulating for children because they are comparing a new perspective to an old known story. Challenge is essential to making the effort and success of the activity meaningful. An example would be having children solve a mystery. The challenge of the mystery makes the work and the reward of solving the problem meaningful.
Fantasy is an excellent way to inspire creativity.
Having children write tall tales, allows them to imagine and take risks. Make sure every lesson, even the short ones, are exciting. I was observing a classroom once when the teacher had a few extra minutes before lunch. She discovered that their butterfly had broken free of its chrysalis. Instead of holding it up and discussing what happened.