It is "understanding of numbers", "operation of numbers" and "common quantities". In the first period, the study of number and algebra mainly revolved around these three themes. Students will learn about different types of numbers, such as integers, decimals and fractions, and understand their meanings and properties. At the same time, students will learn to perform four basic operations and master the basic rules and skills of operation. Students will also learn the common quantity, time, length, weight and so on. , and understand the unit and conversion relationship. Through study, students will establish basic mathematical concepts and operational ability, and lay a solid foundation for subsequent mathematical study.