Why do we use Valiant in primary?

Sydney • Mommy to one baby girl 🎀
I am in the process of writing a talk. I have been given the topic "what does is mean to be valiant?"
Being a primary teacher, the first thing that pops into my head is, why do we use the word valiant for the class names?
For example I teach the Valiant 8 class in primary.
And I also noticed that's the age where they start using valiant in the class name. Before that, they use CTR, like the CTR 7 class.
I'm not sure where I could find an answer to this, I'm sure I could make up an answer "because they are valiant for following Jesus because that's when they get baptized"
And that may be the answer but I have no idea! Does anyone know why?