The expansion of numbers. Primary school mathematics only knows and understands rational numbers, but in the first grade, we should further understand rational numbers from the understanding of rational numbers, as well as through the number axis, reciprocal and absolute value, so as to lay the foundation for the operation of rational numbers.
The operation of numbers. The operation of primary school mathematics learning is the addition, subtraction, multiplication and division of elementary arithmetic, while the starting number operation in grade one is not only the four operations of addition, subtraction, multiplication and division, but also the learning of power, the learning of square root in grade two and so on.
Geometry. Primary school students learn the understanding of geometric preliminary plane figures and three-dimensional figures, and begin to learn the calculation and properties of plane figures in grade one.
Statistical probability. Primary school mathematics is only the preliminary study of statistics, and the first grade begins to learn the calculation and application of statistics, the preliminary study of probability and calculation.