This teaching is a great example of scripture build up. It is easy to skim over readings that we are very familiar with and miss important details. The baptism of Jesus by John the Baptist in the Jordan is covered by all four gospels, so what can we possibly learn from such a familiar record? What are the three aspects of the sign from heaven? What is the significance of this miracle? This was God's benediction on Jesus's life. What does it mean for us today?