at chapter 599 p.2 why all of them dont have leaf forehead protector? does it means they are not yet genin? they will attend the academy entrance exam for genin level.
from chapter 599 page 4 - 11 ---> they have now leaf head protector it means that they are genin that wants to become chunin. Kakashi passed at age 6 and obito also age 6 who failed to become a chunin. During their time if a genin failed to become a chunin at chunin exam does it mean that he will return to the academy? with these we can say that obito study again at the academy until he reach 9 and graduated. Then after 2 years he passed the chunin exam and he was 11 at that time(at page 12). After 2 years again when they are 13 at chapter 599 p.13 they plan to give kakashi a gift.
to summarize by their age;
5 years old -------> they are both studying at ninja academy and graduated
6-12 years old ---> kakashi was at chunin level ninja
6-9 years old -----> obito was sent back to academy to train and graduate
9-11 years old ---> obito wait for chunin exam and passed at age 11
after 2 years at age 13 ----> obito and kakashi do mission at kannabi bridge
so kakashi and obito have same age.
obito graduated 2 times at the academy :shrug: possible?yes