Jeff's adversities in 8th grade are dealing with his friend getting cancer again and dying,facing the risk of being held back due to failing the state test because of the methotrexate damaging his brain,and his brother leaving.
He overcame this adversity with support from his friends and family,Tad helped him study for the test,and his family and Lindsey helped him forward.
"My best friend's heart stopped at 10:32 AM,probably while I was stopping halfway through my ride to grab a hotdog.It wasn't even a good hot dog"
This shows what Jeff feels like after Tads death during his bike ride.
"Then suddenly,Lindsey was right between Tad and Me"
This shows the support of his friends when they did a riot during the state tests.
Tad gets chronic myelogenous leukemia in 8th grade and has to get a bone marrow treatment and other treatments such as gleevec.
He did a beau geste for Jeff by rioting during the state test,and got the state to reconsider holding kids back for failing the test,so everybody would remember him
"But wow,Tad knew how to make a beau geste when it counted."
This shows that tad did a major beau geste before the bone marrow treatment.
"It turns out the answer key to the english was all messed up and when the state auditor's started investigating,they found "significant irregularities" in the way the scorers were trained too."
Tads beau geste had the investigators check the test,making them reconsider the test.
There's nothing,you can do about it,so you go,and they stick you,and you get sick and that's it.
This quote explains how Jeff and Tad went to their treatment bravely
"You're my beau geste.Getting you onto that stage s way more important to me than strolling across it"
This supports the theme because Tad was determined for Jeff to graduate