These are two awesome examples of 2D Animation. I handpicked these two because of the simple and powerful story.

The Last Duet on Earth
https://www.youtube.com/watch?v=L6RSD8m_QOQ

Out of Sight
https://www.youtube.com/watch?v=4qCbiCxBd2M

If you haven't seen them, check them before moving on with the course, or... do whatever you want, but don't say I didn't warned you... I will be discussing those animations in future lessons more than once.