Absolute value is the content of section 1.2.4 in the seventh grade mathematics textbook. Before this, students have learned the basic contents such as rational number, number axis and inverse number, which has paved the way for the transition to this section. Absolute value can not only help students deepen their understanding of rational numbers, but also make necessary preparations for learning the comparative size of two negative numbers and the operation of rational numbers in the future! Therefore, this lecture plays a connecting role in the rational number section.