In John 6 Jesus feeds the 5,000 men supernaturally from 2 fish and 5 loaves.
This great sign moves the people to try to forcibly make Him king.
He leaves and later crosses the Sea of Galilee.
The following day some of those same people seek Him to repeat the miracle but receive correction from Jesus because of their motives and instruction on what food really to seek Him for.
This leads to a wonderful point in John 6:29 concerning salvation.