Renaming Grades

So I've been working on Learning Lynx Classroom  a lot lately, trying to get things ready for the kids to do school there this year instead of all the other sites we've tried.

What I realized is that Grades Playschool through first or second are really sequential. But from 3 up to 8th, you really could do them in any order, the way I have them set up. They really are just sets of information, not leveled, since really once you can read, the only leveled instruction you need is in math, and I don't do math there (because it needs to be individualized and I like Saxon).  Everything else is mostly exposure to information that you adapt as you go to be on whatever level you happen to be on (and this varies widely for gifted kids).

But calling the grades by numbers practically demands you do them in order.

Further, I don't like the idea of the kids dropping a curriculum and moving up without finishing it simply because September rolled around again. I want them to be in "grades" by their year in school for the social simplicity of it (both the homeschool group school, Options, and the greater society find it convenient to say, "What grade are you in?" and want the answer to be related to your age and where the public schools would place you--and I want that social convenience for myself and the kids). But I don't want their social grade to be tied to their learning experience at all. It's too confining. The idea would be that, regardless of what grade they are in, they work steadily at the curriculum they are on until they finish it, and then they move on to another one. (I give them a month off in between as a reward for finishing, plus $3 worth of candy that they get to pick at the store, but that's a separate issue).

So I'm toying with the idea of renaming all the grades, making it easier for you to engage with a curriculum that seems interesting for a year, rather than feeling forced to go forward in order or stop and start based on the public school calendar. So Caleb, for example, would be in fifth grade and doing the _____ level/set/curriculum on Learning Lynx Classroom. It's what to put in that blank that I'm puzzling over.

I already have a "you're ready for this level if....." section for several of the years, and already have a summary of the content of the year on each start page because I was having trouble remembering, while I'm sorting links, what went where.

So what would you call them?

Colors?

Precious stones and metals?

Plants?

Notable people from history?

Mythological beings or creatures?

Greek letters?

Nintendo/cartoon characters?
....


I've strongly considered colors. They're relatively neutral in their connotations and cultural-linguistic valuations (red is not more important, better, or more desirable than yellow, culturally).  I've also strongly considered gemstones/precious metals because of the association it makes with knowledge being precious and school being valuable. I've also considered using tree names because of the association with the organic nature of  growth and strength, and also because all trees have value, but they are different.

What do you think?

If you were going to rename the grades to make them non-sequential, what would you call them?  And why?