1. Central theme: Draw an image or word representing the theme of Unit 4 in the center of the paper or screen. For example, you can draw a big apple with Unit 4 on it.

2. Main concepts: Starting from the central theme, four main concepts are introduced, which are the core content of this unit. For example, these four concepts can be addition, subtraction, multiplication and division. Next to each concept, you can draw a small picture or word to explain it.

3. Sub-concepts and examples: Under each major concept, list relevant sub-concepts and examples. For example, the commutative law and associative law of addition can be listed below, and specific examples are given next to them. Similarly, related sub-concepts and examples can be listed under subtraction, multiplication and division.

Skills of making mind maps;

1. Clarify the central theme: When making a mind map, you must first clarify the central theme and put it in the center of the mind map. The central theme is a general summary, and all other contents should revolve around it. This can ensure that the content of the mind map does not deviate from the theme, and it is also conducive to the coherence and organization of thinking.

2. Use keywords: When making mind maps, use keywords to summarize each theme and concept. Key words should be short and clear, which can accurately express the meaning of each topic and concept. Using keywords can avoid using long sentences or large paragraphs in mind maps and make mind maps more concise and easy to remember.

3. Use colors and images: Colors and images can increase the attraction and interest of mind maps. Different colors and images can be used to distinguish different themes and concepts, making mind maps more intuitive and easy to understand. At the same time, images can also help people better remember the contents of mind maps.

4, concise and clear: when doing mind mapping, try to be concise and clear. Avoid using too many words and paragraphs in mind maps to avoid confusing and confusing readers. At the same time, delete unnecessary words and information to make mind maps more concise and easy to understand.