The Doctor communicates with people in the present while he is in the past to warn them about the Weeping Angels and impending danger.

The Doctor and Clara are chased to the center of the TARDIS and learn to trust each other.

This video describes the process of how scientist make discoveries and come to conclusions using the scientific method.

The Doctor takes Clara time traveling on the TARDIS and she questions whether the Doctor sees her as a ghost or living person after seeing the entire life cycle of the Earth.

After investigating a broken portrait, a time votex appears and the Doctor decides to jump through. He then meets himself in a past life and they compare themeselves.