Life as an elementary school kid in Japan is pretty laid-back when it comes to using Keigo.
Elementary school in Japanese is called:
We are taught to use Keigo when speaking to our teachers, but when talking with friends or even adults outside of school, we still use Tameguchi.
I remember using Tameguchi with my friend's older brothers and their parents, and no one minded at all.
As of writing this, I play indoor soccer/football twice a week.
There are a few elementary school kids playing with us and they always talk to me and other adults in Tameguchi.
But as we progress through elementary school, we start to use Keigo more and more, especially in formal settings like class presentations or when speaking to older teachers.
Some teachers are pretty cool and don't mind if we use Tameguchi, but others, especially older teachers, expect us to use Keigo when speaking with them.
Overall, using Keigo as an elementary school student in Japan is all about knowing when and where to use it, rather than being forced to use it all the time.
Even though we use it more in school, we can still talk to our older friends and even grown-ups using Tameguchi without getting into trouble.