Snails crawl at the bottom of the well at a depth of 10 meter, climbing 5 meters during the day and sliding down 4 meters at night. How many days does it take for snails to climb to the wellhead?
(1) analysis
(1) One day and one night: climbed 5-4= 1 meter.
(2)5 days later: I climbed 5 meters.
(3) Last day: Snails don't have to spend the night in the well, but can climb out during the day. On the last day, the little snail actually advanced 5 meters, which was different from the previous days!
(4) So the snail crawled out in six days.
(b) Problem solving skills
Two-stage thinking
(1) The situation these days.
(2) the situation on the last day.