1. Establish good study habits: keep a certain amount of study time every day and insist on completing homework and review tasks. Developing good study habits can help children master mathematics knowledge better.

2. Understanding concepts rather than rote learning: Mathematics is a subject that needs to be understood and applied, not just memorizing formulas and calculation methods. Help children understand mathematical concepts and cultivate logical thinking ability.

3. Do more exercises: through a lot of exercises, consolidate what you have learned and improve your problem-solving ability. You can choose some workbooks or online resources suitable for your child's age and ability.

4. Create real situations: connect mathematics knowledge with real life and let children apply what they have learned in real situations. For example, through shopping, cooking and other activities, let children perform simple addition, subtraction, multiplication and division operations.

5. Use games and interactive learning: Math games and interactive learning can improve children's learning interest and participation. You can use some math game software or online platform to let children learn math while playing.

6. Ask for help: If the child encounters difficulties or doesn't understand, ask for help in time. You can seek answers and guidance from teachers, parents or other learning resources.

7. Cultivate problem-solving ability: Mathematics is a good tool to cultivate children's problem-solving ability. Encourage children to think and solve problems, and cultivate their logical thinking and creativity.

In short, learning junior high school mathematics well requires persistence, understanding and practice. Through good study habits, understanding concepts, doing more exercises, creating practical situations, using games and interactive learning, seeking help and cultivating problem-solving ability, children can be helped to master mathematics knowledge better.