Why does Jess need to be the fastest in his class in Bridge to Terabithia?

Jess needs to be the fastest in his class because he likes winning.  The narrator tells readers that Lark Creek Elementary does not have a lot of athletic equipment.  Anything that the school does have, the sixth and seventh graders nab right away.  The third through fifth graders are left with nothing other than having foot races across the field.  The previous school year, during one of those races, Jess had beaten everybody else, and...

Jess needs to be the fastest in his class because he likes winning.  The narrator tells readers that Lark Creek Elementary does not have a lot of athletic equipment.  Anything that the school does have, the sixth and seventh graders nab right away.  The third through fifth graders are left with nothing other than having foot races across the field.  The previous school year, during one of those races, Jess had beaten everybody else, and he got a real taste for winning.  

One time last year Jesse had won. Not just the first heat but the whole shebang. Only once. But it had put into his mouth a taste for winning.

Jess needs to be the fastest kid in the class, because it will change the way other kids look at him.  The narrator also tells readers that Jess is the odd kid who draws a lot.  

Ever since he'd been in first grade he'd been that "crazy little kid that draws all the time." But one day - April the twenty-second, a drizzly Monday, it had been - he ran ahead of them all, the red mud slooching up through the holes in the bottom of his sneakers.

For the rest of that day, and until after lunch on the next, he had been "the fastest kid in the third, fourth, and fifth grades," and he only a fourth grader.

Jess believes that if he can consistently be the fastest kid in school, his classmates will revere him instead of thinking that he's odd.  

He could hear the third-grade boys screaming him on. They would follow him around like a country-music star. 

Lastly, Jess needs to be the fastest kid in order to earn his father's approval.  Jess desperately longs for his dad's love and attention.  His dad works long hours, so he is not home very much.  The dad also isn't fond of Jess doing art.  Jess figures that if he excels at running, his dad will be proud enough to want to spend more time with him.  

Maybe Dad would be so proud he'd forget all about how tired he was from the long drive back and forth to Washington and the digging and hauling all day. He would get right down on the floor and wrestle, the way they used to. Old Dad would be surprised at how strong he'd gotten in the last couple of years.