1. Determine the position of the observer: it is necessary to determine the relative position of the observer and the observed object. For example, if a person stands in front of a box, his line of sight and the axis of the box should be on a vertical plane. In this way, the observer's position can be found and marked.

2. Marking important points: After determining the position of the observer, it is necessary to mark important points on the observed object. For example, if a person looks at a box from one side, he can see three sides of the box. Mark important points on each face, such as the edge of the box or special marks.

3. Draw a line of sight and verify it: Draw a line along the observer's line of sight starting from his eyes. This line should point to a point on the observed object. This point is the observation point. Need to verify whether the observation points found are correct. If the observation point seen from other angles is consistent with the observation point found before, then this observation point is correct.

Primary school mathematics learning methods

1. Understand the basic concepts of mathematics: for each new topic, make sure you understand its basic meaning. This includes understanding the concept of numbers, addition, subtraction, multiplication and division, fractions, decimals, graphs and measurements.

2. Pay attention to practice and review regularly: learning mathematics is not only to cope with exams, but more importantly, to understand and use this knowledge to solve practical problems. By solving practical problems, we can better understand the practical significance of mathematical concepts. Review and review what you have learned in class regularly. This can help you consolidate your memory and better understand and use this knowledge.

3. Cooperative learning and group activities: Studying and discussing math problems with classmates can enhance your understanding ability and gain a new perspective from their viewpoints. Learning mathematics with different learning methods, such as models, charts and games, can enhance your understanding and interest.

4. Find the law of the problem and ask for help: For some complex problems, finding the law can help you better understand the problem and find solutions. Don't be afraid to ask for help if you encounter difficult or incomprehensible problems. You can ask your teachers, parents or others who know more.