1. Addition, subtraction, multiplication and division of fractions and decimals: this part is the core content of fractions and decimals in the whole primary school, and it needs to be proficient in various algorithms and skills.

2. Multiplication and division of fractions and decimals: This part mainly studies the multiplication and division of fractions and decimals, and needs to master the multiplication formula table and the reciprocity relationship between fractions and decimals.

3. The application of fractions and decimals: This part mainly studies how to use fractions and decimals to solve practical problems, and needs to master problem-solving methods and skills.

4. Properties and calculation of geometric figures: This part mainly includes the properties and calculation methods of plane figures (such as rectangles, squares, triangles, etc.). ) and three-dimensional graphics (such as cuboids, cubes, cylinders, cones, etc. ).

5. Data collection, collation and analysis: This part mainly studies how to collect, collate and analyze data, and needs to master statistical tables, bar charts, line charts and other methods to represent data.

6. Preliminary understanding of algebraic expressions: This part mainly studies the letter representation of numbers, and it is necessary to master the writing norms and arithmetic rules of algebraic expressions.

7. Preliminary understanding of the equation: This part mainly studies the solution of linear equation with one variable, and it is necessary to master the basic steps and methods of solving the equation.

8. Preliminary understanding of inequality: This part mainly studies the solution of linear inequality in one variable, and it is necessary to master the basic steps and methods of solving inequality.

The above are some key contents of the second book of sixth grade mathematics, I hope it will help you. In the process of learning, we should pay attention to understanding and application, and do more exercises to consolidate what we have learned.