Jesus film 11 - Calling of 12

Read Luke 6:12-16 (NIV)
¹²One of those days Jesus went out to a mountainside to pray, and spent the night praying to God. ¹³When morning came, he called his disciples to him and chose twelve of them, whom he also designated apostles: ¹⁴Simon (whom he named Peter), his brother Andrew, James, John, Philip, Bartholomew, ¹⁵Matthew, Thomas, James son of Alphaeus, Simon who was called the Zealot, ¹⁶Judas son of James, and Judas Iscariot, who became a traitor.

1. Jesus called twelve men. For which job or jobs? Before He called those men, what did Jesus do and how long did that take?
   

2. Why did Jesus call 12, and not less or more?