These verses look like a re-run of the feeding of the 5,000.  But it is not, not really.  It is a separate episode (Mark 8:19-21), but so similar that the disciples should have been prepared and aware of the training the Lord Jesus was giving them.  Jesus even set them up with a question to demonstrate that they had understood the previous lesson - and they failed the test!

Another large crowd had gathered.  It happened wherever Jesus went.  This time the teaching lasted three days and by the end of that time the people were very hungry.  Knowing that Jesus was compassionate by nature, knowing He wanted to supply the crowd with food, and knowing that He had already fed 5,000 (Mark 6:35-44) - they should have turned to Him and said, "Master, we believe that you can feed them!"  Instead, they complained that there were no bread shops for miles around. Jesus even gave them a clue by referring back to the earlier massive picnic by asking exactly the same question as before “How many loaves do you have?” (Mark 6:38).

The trainee apostles had not understood what Jesus was doing.  Instead of responding in faith, they persisted in their worldly thinking, even though the King of heaven was with them (Mark 9:19).  They were living alongside Jesus, but His life was not inside them.  They did not connect their experience of His power in a previous similar situation, with the possibility that Jesus might act in the same way again. Some like to defend the disciples by assuming that they were confused by the random nature of Jesus' ministry; but that cannot be true as He acted with compassion and transformed the lives of all who trusted Him (Mark 6:34).  Some assume that because they did not have the indwelling Spirit, then they could not link Jesus' power with a new situation; but demonised people (Mark 1:24), sick (Mark 10:47-48) and outcasts (Luke 19:7-10) had no difficulty in recognising His power.    

How many lessons, painfully learned, have we forgotten?   What a lot of spiritual education has apparently gone to waste, as we make the same mistakes again and again.  This passage forces us to consider how the Lord has met with us, and our circumstances, in the past.  Instead of floundering at the next impossibility, it is important to tell the Lord that you trust Him to sort it (and that you are willing to cooperate!).