10 cm.

Suppose there is a pond with infinite water. At present, there are two empty kettles with a capacity of 5 liters and 6 liters respectively. The problem is how to get 3 liters of water from the pond with only these two kettles.

Answer: Fill a 5-liter pot and pour it into a 6-liter pot. Then pour it into a 6-liter pot until it is full. At this time, there are 4 liters of water left in the 5-liter pot. Pour the remaining 4 liters of water into a 6-liter pot. At this time, there are only 4 liters of water in the 6-liter pot. Then fill the 5-liter pot and pour it into the 6-liter pot until it is full. At this time, there are only 5 liters of pots left.

introduce

Interesting mathematics has both the rigor of mathematics and the fun of games. It is the lubricant for students to learn mathematics now. Diversified learning methods promote the development of multiple intelligences.

We must change the original single and passive learning style, establish and form diversified learning styles with the goal of fully mobilizing and giving full play to students' subjectivity, promote students' active and personalized learning under the guidance of teachers, pay attention to cultivating students' critical consciousness and skepticism, encourage students to question books, surpass teachers, and appreciate students' unique and personalized understanding and expression.