Xin-Jia Er-Lu or Cannon Fis consists mainly of Fa Jin or Energy release movements that can be seen in Lao-Jia Yi-Lu form mainly in the practice of punching.
Where Lau-Jia Yi-Lu teaches mainly the Yin side of Tai Chi learning to flow and join with an opponent Xin-Jia Er-Lu teaches the Yang side that of striking and attacking with great power while maintaining a relaxed state.
Movements can be sudden and supprising or with intrecate wind ups. It is always advised to understand and practice the Yi-Jia forms before progressing to the Er-Lu forms. I am sure Rebecca will be able to fill us all in on what it was like when she gets back to her classes this week.