Simple:
* The child's imagination ran wild as she built a castle out of blocks.
* Artists rely heavily on their imagination to create unique works of art.
Descriptive:
* The author's vivid imagination transported readers to a world of magic and wonder.
* Her imagination conjured up fantastical creatures and far-off lands.
Figurative:
* The possibilities were endless, limited only by the bounds of our imagination.
* With a burst of imagination, she solved the seemingly impossible puzzle.
In a quote:
* "Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world." - Albert Einstein
You can choose the sentence that best fits the context you need.