Describe Maya achievements in writing, mathematics, and astronomy, and explain the Maya as city-states rather than one single empire.
The Maya civilization built dozens of city-states -- Tikal, Copan, Palenque, and others -- across the Yucatan Peninsula and Central America, each with its own king, not one single unified empire like Rome or Mali. During the Classic Period, roughly 250 to 900 CE, these cities built towering stone pyramids and temples, competed and sometimes fought with each other, and developed the most advanced writing system in the Americas before European contact: a system of glyphs that could record names, dates, and historical events in detail, not just pictures.
Maya mathematicians independently invented the concept of zero as a placeholder, centuries before it reached Europe, and Maya astronomers tracked the movements of the sun, moon, and especially Venus with remarkable precision using naked-eye observation alone. They combined this into the Long Count calendar, a system for tracking dates across huge spans of time. Around the 800s and 900s CE, many southern Maya cities were abandoned -- historians point to a combination of prolonged drought, warfare between city-states, and environmental strain from supporting large populations, rather than one single cause. Importantly, the Maya people did not disappear: cities in the northern Yucatan continued for centuries afterward, and millions of Maya people live in Mexico and Central America today, many still speaking Mayan languages.
Mastery looks like: They can explain that the Maya were city-states rather than one empire, name at least two major achievements, and state that Maya people and culture continue today.
Common stumbles: Assuming the Maya were one unified empire like Rome, or believing the Maya civilization "vanished" rather than changed and continued.