In the primary school curriculum or the Olympic Games, we often see the problems of snails climbing wells and bears climbing trees, which many junior students always can't understand. That's because I think the problem is complicated. In fact, I just need to draw a line segment to help me understand, and I can work it out soon.
Today we use line segments to express such topics. Let's see if it is easy to understand.
Please see the picture below:
This kind of question is nothing more than climbing a few meters and then dropping a few meters, asking how many meters you can climb to the top.
For senior students, it can be well understood, such as the topic that the top 2 meters can be directly pushed to the top and will not slide down again. According to the meaning of the question, the climbing height per minute is 2- 1= 1 meter, and the remaining height except the top 2 meters is 1 meter per minute, that is, 9-2=7 meters, 7- 1 = 7 minutes, plus the top 2 meters needs 65438+.
But how should we treat junior students? The suggestion for junior students here is to draw line segments directly.
Look at the picture. In the lower grades, you can draw a line to show that the bear begins to climb down from the tree. According to the topic, it means to climb 2- 1= 1 meter per minute, so it takes 1 minute to climb 1 meter and 7 minutes to climb 7 meters. At this time, there are 2 meters left from the top of the tree. When the bear climbs 1 again, the last 1 minute climbs 2 meters, while the previous one climbs 1 meter every minute, so the bear 1 * * uses1+1+.
Finally, let's look at another topic, snails climb wells. If you add another turtle, can you still work it out?
The well is known to be 9 meters deep, and snails and turtles climb up from the bottom of the well at the same time; Snails climb 2m during the day and descend 1m at night, while turtles climb 3m during the day and descend 1m at night. Excuse me, how many meters is the snail from the wellhead when the tortoise climbs to the wellhead?
Let's use our brains to see how to draw pictures and how to solve this problem.