What cause the season?

TASK:
In the videos, are the seasons similar at the same time in the Northern and Southern hemispheres?
In the videos, does the length of the day change with season?
In the videos, are there any special locations?
What is the cause of the seasons?
In January, which hemisphere (North or South) is most perpendicular to the Sun?
Explain how the tilt of the Earth's axis causes the seasons vary over the course of the year.

You need to see the videos and can use your book.