Make Your Own Zodiac
When many people think of the zodiac, they think of newspaper sections that tell you how your day will go based on what month you were born in. But that's just one way the astrological signs are used, and zodiacs (most notably the Latin one and the Chinese one) incorporate many different topics and features. Whether you place any stock in astrology or consider it a bunch of baloney, the concept of matching elements, ideas, and symbols from various topics can be a great way to put your students' knowledge to the test and to expand it.
Don't worry about the original zodiacs so much, and forget about divination; instead, consider the different building-blocks for a zodiac, and let your students find patterns and create their own.
This project probably works best if students are in groups of two or three.
In the Latin zodiac, people are placed into categories based on their birth-month. In the Chinese one, it's based on their birth-year. Your students should determine the qualifications for their own zodiac. Maybe it's the time of day someone was born. Or how long they can hold their breath. Or the first letter of their name. Or maybe it's something each person could choose, like their favorite article of clothing or school subject. The possibilities are wide open.
Aim for about 12 categories (I wouldn't go more than 15 or much less than 8).
Next the students should consider different types of symbols, and assign one symbol from each type to every category. Here are some different subjects the students could choose from:
animals (including fictional ones)
characters (maybe instead of mythological identities, they can choose from their favorite fandom)
Students don't need to consider all of these; maybe two or three will suffice. Or you might want to be the one that decides which subjects your class should use.
Your students could also consider which traits might be common for people of that category. Here are some ideas (if you use one for any category, you'll need to use it for the rest of them as well).
personality (smart, funny, kind, adventurous, etc.)
physical traits (strong, fast, beautiful, etc.)
skills (social, musical, artistic, scientific, mathematical, etc.)
superpowers (kids can get silly with this one)
You may want to encourage students to only use positive traits.
Also, a single trait can appear in more than one category, so long as those category don't have more than just that one trait in common. In other words, traits don't need to be unique, but the collection of traits applied to any category does need to be unique.
Syncing Traits and Symbols
All these elements shouldn't simply be thrown together haphazardly; there should be some reason to it. Students need to think about what goes together (and should be able to defend their decisions later).
Here's an example: Suppose we start with the personality trait of cool, calm and collected. What animal might fit that? Otters. They like to just chill in the water, having a good time. As for colors, blue is a 'cool' color, and it's very calming to see blue.
Or maybe peacocks, beautiful, beaches, and roses go together. There's not a right answer here; it's up to the students' subjective reasoning. As long as they do have a reason, it's fine.
If you want to give you students more of a challenge, don't let their decisions be purely subjective. Require that they do a survey.
Once they've determined their categories, students can ask other people in their school what their favorite colors are, what animals they think they resemble, what skills they have, etc. Once they've collected the results, the students should try to find patterns. For example, they may find that people born in the month of June (at least among their friends and schoolmates) tend to be musicians and/or love mountains. The patterns they find can then fit into the zodiacs.
Displaying the Zodiac
The most logical way of compiling the features is likely in a table. But a simple google image search can give your students more ideas. Make them think of how to communicate their information visually, but in a way that's easy for readers to find the details of their own categories. The symbols should probably be expressed through images, while traits can be written.
Once it's ready, you could have each team present their zodiac to the class, or you could have individual students look at their category in other people's zodiacs and see if there's anything interesting (perhaps one zodiac hits the nail on the head for them, or perhaps multiple zodiacs agree on one particular trait or symbol).