There are many ways to introduce positive and negative numbers. The textbook introduces two familiar examples: temperature and altitude. 5℃ higher than 0℃, 5℃ lower than 0℃ and-5℃; It is 8848m higher than the sea level, and it is 8848m lower than the sea level155m, and it is-155m. From these two examples, it is natural to call numbers greater than 0 positive and numbers with "-"negative; 0 is neither positive nor negative, but a neutral number, representing the "benchmark" of measurement. Introducing positive and negative numbers in this way will not only help students correctly use positive and negative numbers to represent quantities with opposite meanings, but also help students understand the size nature of rational numbers. Understand negative numbers as numbers less than 0. The concept of "quantity with opposite meaning" does not appear in textbooks. This is to avoid or dilute this concept. The purpose is to reveal the nature of positive and negative zeros and help students understand the concept of positive and negative numbers correctly.

Simply put, greater than 0 is a positive number and less than 0 is a negative number.