1. When comparing the sizes of China and the United States, it is clear that China has a larger area.2. According to Chinese geographical textbooks, China's land area is approximately 9.6 million square kilometers. When including its territorial waters, this figure rises to around 9.68 million square kilometers.3. The United States, on the other hand, covers an area of about 9.37 million square kilometers. The five Great Lakes, which straddle both the U.S. and Canada, have a combined area of approximately 260,000 square kilometers, with the U.S. portion being about 170,000 square kilometers.4. When factoring in the area of the Great Lakes and other water bodies, the total area of the United States is roughly 9.629 million square kilometers.5. To illustrate the size of China's landmass, one can showcase a map of the country and highlight the five largest provinces and autonomous regions, reminding students to read numbers in their correct order of magnitude to avoid errors.6. Numbers should be read in levels, from right to left, with each level containing four digits. For example: unit level, ten-thousand level, hundred-thousand level, and so on.7. Returning to the map of China, explain how to compare the sizes of these numbers and provide exercises to reinforce this knowledge.8. Finally, introduce the methods of rewriting multiples of ten thousand and ten million, and provide exercises to solidify the learning.