Explaining Induced Drag??

[pipertommy]

Hi All,
If you were teaching a student about induced drag how would you explain the tilting aft of the total lift force? Forming the angle for Induced Drag?

I understand the high to low airflow resulting in vortex at wing tip and the downwards part of the vortex acting on the trailing edge of the wing. This produces a downwash.

The part which I`m loosing it, is the average relative airflow/AoA. Why is this formed? Due to the trailing edge downwash?

Thanks.