Question: I'm trying to recall a story I read in the early-to-mid 80s. It was a school library book and probably old at the time. I don't recall any details of the cover. I do not believe it is [Lost Race of Mars](https://scifi.stackexchange.com/questions/105552/kids-sf-chapterbook-about-mars-with-three-eyed-martian-animals-and-hidden-old).

The protagonist is a teenager on Mars. A new authority figure comes into his life, either a teacher or an administrator of some sort, someone who is not flexible or patient with the customs of the people on Mars. For example, teenagers routinely painted their helmets for individuality - I believe the protagonist painted his like a tiger - and the authority figure ordered them to remove the paint.

Protagonist has a "pet" of local Martian fauna. At one point in the story, protagonist discovers that their "pet" is in fact the immature version of the adult Martian lifeform, something that had not been understood before that.

The overall arc of the story is Protagonist's rebellion against the new Authority, which I believe succeeded in the end, perhaps helped by his new understanding of or with the Martian natives.

Answer: 
Sounds like "**[Red Planet](https://www.isfdb.org/cgi-bin/title.cgi?1328)**" by **Robert Heinlein** (1949).

I read it a long time ago and have forgot much of the plot but I remember the issues between the young protagonist and the school director on Mars.  

There's a scene involving his mask that matches your description:

> 
> Although this face occupied the whole screen and was weirdly
> distorted, Jim had no trouble in placing it as a colonial's respirator
> mask. What startled him almost out of the personal unawareness with
> which he was accepting this shadow show was that **he recognized the
> mask. It was decorated with the very tiger stripes** that Smythe had
> painted out for a quarter credit; it was his own, as it used to be.
> 
> 
> 

The protagonist also had a pet named Willis that is later shown to be a child-like stage of the three-armed/legged Martians.
Red Planet by Robert A. Heinlein
Plot matches on all points
The authority figure is the new headmaster