The Jade Emperor holds a race across a river, and the first twelve animals to reach the far bank each get a year. How the rat won, how the ox helped, and why the cat never forgave either of them.
The twelve zodiac animals are usually presented as a list to memorise. The folktale explains them instead: the Jade Emperor announces a race across a river, and the order in which the animals arrive becomes the order of the years. The rat comes first by riding on someone else's back, the ox carries others across, and the cat ends up out of the calendar and permanently at odds with the rat.
Told as a story, the order stops being arbitrary and becomes something students can retell, which is a much better test of comprehension than naming twelve animals. A2-B1, clear narration, and it works as reading and listening practice as well as a culture lesson.