在德州。公校。是我们学区的一个数学program—— 好了。贴题。 When the 1,000 students are finished, which locker doors are open? Explain why your answer makes sense. What kind of numbers are these? 阅读材料在这儿—— There are 1,000 lockers in a long hall of Westfalls High. In preparation for the beginning of school, the janitor cleans the lockers and paints fresh numbers on the locker doors. The lockers are numbered from 1 to 1,000. When the 1,000 Westfalls High students return from summer vacation, they decide to celebrate the beginning of the school year by working off some energy. The first student, Student 1, runs down the row of lockers and opens every door. Student 2 closes the doors of Lockers 2, 4, 6, 8, and so on to the end of the line. Student 3 changes the state of the doors of Lockers 3, 6, 9, 12, and so on to the end of the line. (This means the student opens the door if it is closed and closes the door if it is open.) Student 4 changes the state of the doors of Lockers 4, 8, 12, 16, and so on. Student 5 changes the state of every fifth door, Student 6 changes the state of every sixth door, and so on, until all 1,000 students have had a turn. Consider this question: When all the students have finished, which locker doors are open? Make a conjecture about the answer to this question. Then, describe a strategy you might use to try to find the answer.
好了。贴题。
When the 1,000 students are finished, which locker doors are open? Explain why your answer makes sense. What kind of numbers are these?
阅读材料在这儿——
There are 1,000 lockers in a long hall of Westfalls High. In preparation for the beginning of school, the janitor cleans the lockers and paints fresh numbers on the locker doors. The lockers are numbered from 1 to 1,000. When the 1,000 Westfalls High students return from summer vacation, they decide to celebrate the beginning of the school year by working off some energy.
The first student, Student 1, runs down the row of lockers and opens every door.
Student 2 closes the doors of Lockers 2, 4, 6, 8, and so on to the end of the line.
Student 3 changes the state of the doors of Lockers 3, 6, 9, 12, and so on to the end of the line. (This means the student opens the door if it is closed and closes the door if it is open.)
Student 4 changes the state of the doors of Lockers 4, 8, 12, 16, and so on.
Student 5 changes the state of every fifth door, Student 6 changes the state of every sixth door, and so on, until all 1,000 students have had a turn.
Consider this question: When all the students have finished, which locker doors are open? Make a conjecture about the answer to this question. Then, describe a strategy you might use to try to find the answer.
谁说美国公校数学简单？
跑来问我这个题，我当时正忙，觉得一时半会儿和他讲不清楚。
后来娃爸回来，俩人写写画画，娃爸给娃讲清楚了。
今天突然想起来这道题，发上来周末做个题大家娱乐一下。
旱的旱死涝的涝死。 公校四年级可以跟学校报amc 8了，但也不代表学校学生整体水平有多高
算式的抽象能力高于画图。能用算式，当然可以不画图。如果老师非要画图，是老师脑子有病
不用凡啊。一开始不就说了是学区的一个数学program。那肯定不是随便一个娃想进就能进的啊。
这个program就是我们当地学区的一个数学program。从每年年终的数学和阅读测验中综合出来成绩，然后给家长发邮件，邀请小孩enroll。
据我小孩回来说，学的数学知识高出两个年级。
不过我好奇的是，他现在这个学校，四年级在这个program里面的一共5个小孩，其中有3个都是从其他学校转过来的（因为不是每个学校都有这个program）。我小孩也是转过来的。我确实没想到这么少。
平时大家一起上别的课，只有数学课是单独出来上。
说了半天，这和美国公校数学简单还是难🈶️半毛钱关系吗？
自己教多累，我就直接让娃自学，省心了，khan 或者ba都有录像，我听了一会儿，觉得ba的视频说得更好，比我说得好多了。
关系就是，那些张口就说美国公校数学简单的，片面了。
我认为多数公校数学还是正常教的。
当然，我贴的这个也是一个片面的例子。
以片面驳片面。就是我的逻辑。
不是那个意思，是有些2，3年级的，根本没学过的内容，你咋教？一步跳级？？ 我正在想怎么给娃讲的时候，娃已经自己画图算出来了
这和公校没关系。这个问题题目就是 The lock problem， 最早是80年代的美国高中的题目，当时大概只有100，上课时，可能会有100纸片去模仿开门关门。 现在，估计都是放到美国的大学了。你觉得是用数学方法，其实和画圈一样，就是让学生一个门一个门的开关。 只是有些聪明的学生，可以通过数学方法解决
1000个，有的老师会有硕大的桌子，好多同学一起动手，开关门。
三十年前看到这题的时候是开灯。现在改开门了？
按你的说法所以别的娃数学学的简单主要是他们不够聪明，没法进入你娃的math team
我们这里也是。我们年级也挑5个，每周一次，只是数学不一样。新泽西