The season introduces William Hartnell as the First Doctor, an alien who travels through time and space in his TARDIS, which appears to be a British police box on the outside. Carole Ann Ford is also introduced as the Doctor's granddaughter Susan Foreman, who acts as his companion alongside her schoolteachers Ian Chesterton and Barbara Wright, portrayed by William Russell and Jacqueline Hill, respectively. Throughout the season, the Doctor and his companions travel throughout history and into the future. Historical stories were intended to educate viewers about significant events in history, such as the Aztec civilisation and the French Revolution; futuristic episodes took a more subtle approach to educating viewers, such as the theme of pacifism with the Daleks.