Do you actually think that Rowdy came to Arnold's door because he was bored? If not why do you think he came? Why did Arnold decide to play basket ball with Rowdy, other thank knowing that Rowdy would never change?

I do not believe that Rowdy knocked on Arnold's door just because he was bored.  If Rowdy was just bored he would have found something entertaining to do, rather then going to see his ex-friend's (who he presently hates).  Rowdy realized that he was bored because it was summer and he no longer had his best friend.  In the past, Arnold and Rowdy would spend every minute of every summer together, keeping each other occupied.  On page 17, Arnold says about Rowdy, "It's like he's a family member, an extra brother and son."  Arnold's statement about Rowdy demonstrates the strong relationship between Rowdy and Arnold.  Rowdy also knew that they were best friends...like brothers.  Arnold loved Rowdy and Rowdy loved Arnold.  Although the two of them were not family, they treated each other like family.  They played with each other, they talked to each other when they were down, and they fought each other.  They behaved liked typical siblings; even though they argued and didn't like each other at time, they always loved each other.  Arnold could have said no to Rowdy's offer of playing ball, but I think he knew that would have been the wrong choice and something that Arnold would have regretted for his entire life.  Arnold knew that if he had said "no", Rowdy would have walked away and not given him another chance.  Arnold always wanted to keep his friendship with Rowdy, even if it was not the same as it was before Arnold moved schools.  Both Arnold and Rowdy realized that their lives were too short to lose friendships, especially one as close and strong as theirs.