Social studies curriculum can vary widely, from one school to the next. Typically, the early years may cover little more than studying the meaning behind holidays like Thanksgiving, Lincoln's birthday, and Martin Luther King Day. Social studies textbooks usually arrive by second or third grade. Children may begin to learn how groups of people work together, and how different cultures live. They're usually taught about the different jobs performed, the tools used, and the purpose each job serves. Later, history enters the mix, as children study the way people lived long ago. During the intermediate grades, four through six, history and social studies involve more reading. Children are sometimes asked to memorize certain dates, facts or figures. Hopefully, the school won't rely on these exercises alone. Some classes present music, art or literature from the time period being studied, to give students a better feel for the culture and era. Or, they may engage in class projects, like building a model of a log cabin or pyramid. Common topics of study include Native Americans, the Incas, ancient Egypt, and the Middle Ages. In addition to the people's everyday life, children also learn about the culture's government, political leaders, and wars.