This week's Torah portion, Ki Tisa, contains two pivotal events in the relationship between the Almighty and the Jewish people:
the sin of the Golden Calf and
subsequently gaining forgiveness for that sin (articles 4 - 6).
We also read an additional Torah section in Shul, called "Parah" (article 6) in preparation for the Passover Festival.
The  lead article relates to the famous Shabbat section (31:12-17) in the Reading.