learning curve (noun)

1. Why did the math book look sad? Because it had too many learning curves!

2. As the characters explored the haunted house, they realized that the learning curve to survive this nightmare was steep.

3. In the movie, the two protagonists meet at a summer camp and their love story unfolds with a beautiful learning curve.

4. The superhero had to go through various challenges and obstacles, each adding a new learning curve to their journey.