看看这些小学的数学题 你能做出几道?

yishun2009

小二的:
A. Fred has 374 more badges than Jacky. How many more badges must Fred give to Jacky so that Fred would only have 98 more badges than Jacky? ( 不会吧, 让小二的学生做这种题, 太邪乎了吧?)

B. Amy has 800 g of chocolate. She ate 500g and gave the remaining chocolate to Alex and Mimmy. Alex and Mimmy received the same mass of chocolate. How much chocolate did each of them receive? ( 这到题还将就)

小三的( 可不是你想的那个小3啊):
A. Yong Lin has $31.2. If she gives $3.2 to her brother, she will have less $4.5 than her brother. How much money does her brother have? ( 感觉比小二A题简单)

B. Jodie started work at 7.56AM. She had lunch at 12.30PM to 1.45PM. She resumed work and finished her work at 6.15PM. How long did she work? Please give your answer in hours and minutes.

小四的:
Bus service 123 goes from Town B to Town A at an interval of half of an hour. Bus service 456 goes to the same town at interval of 45 minutes. Suppose both bus services set off Town A at the same time, after how  long will both services be at Town B? ( 这个是脑筋急转弯吗? 感觉给的条件不充分啊, 为何惜字如金?))

小五的:

A. A restaurant charges $68 per person for a buffet dinner. Forevery 4 people, one will dine for free. Mr Tan brought his family to therestaurant for Chinese New Year and paid a total of $544. How many people arethere in Mr Tan’s family? ( 不会是在考英语吧?)

B. Frank and Gary have some stamps. The ratio of Frank’s stampto Gary’s stamps was 11:13 at first. Gary decided to give Frank 30 stamps andthe ratio becomes 7:5.

a.     How many stamps does Gary have now?

b.     How many stamps did Gary have in the firstplace?

小六的( 上难度了):

Candice and Megan were each given a paragraph of words to type. If Candice typed 15 words per minutes and Megan typed 10 words per minutes. Candice would have 20 more words untyped when Megan is finished with her paragraph. If Candice typed 10 words per minute and Megan typed twice as fast, Candice would have 220 words untyped when Megan is finished with her paragraph. How many words were there ineach person’s paragraph?

yishun2009

我的总体感觉是, 围绕着2元1次方程, 甚至是3元1次方程, 小六必考, 小五小四小三也上, 小二也开始接触. 照这趋势下去, 小一也要会解方程? 太超前了!

理解题意也很重要, 英语能力很关键.

男人如树

不需要方程也能解。人家是训练数学的基本思维，我们学了方程，就一切依靠方程了。

看来你没陪孩子做过题啊。

yishun2009

男人如树 发表于 31-8-2012 10:45
不需要方程也能解。人家是训练数学的基本思维，我们学了方程，就一切依靠方程了。

看来你没陪孩子做过题啊 ...

关于上述小二A题, 非常抽象, 要用代数, 用了代数而不写下方程式, 很难表示两者关系, 很难解释. 所以如果不用方程来解, 还请赐教.

jjrchome

yishun2009 发表于 31-8-2012 11:02
关于上述小二A题, 非常抽象, 要用代数, 用了代数而不写下方程式, 很难表示两者关系, 很难解释. 所以如果 ...

(374-98)/2 = 138

jjrchome

yishun2009 发表于 31-8-2012 11:02
关于上述小二A题, 非常抽象, 要用代数, 用了代数而不写下方程式, 很难表示两者关系, 很难解释. 所以如果 ...

小二的学生是这样计算的：



不过，这道题对小二学生来说是一道难题。

yishun2009

jjrchome 发表于 31-8-2012 11:09
(374-98)/2 = 138

这个答案是正确的, 但如何向孩子解释?

代数, 方程, 还是最容易让人理解的. 比如:
F=J+374;  F'=J'+98; if X is the answer, then F'=F-X,  J'=J+X. 通过这些关系, 可以推倒出 X = (374-98)/2 = 138.

看见版主的解法了, 图示法, 比较直观, 好!

jjrchome

我以前曾经发过一些关于model drawing的资料。楼主可以看看下面这个帖子（按‘箭头“就可以播放了）：

http://bbs.sgchinese.net/thread-5201419-1-1.html

yishun2009

看到这种A给B了什么, 然后A比B多多少, 等等类似的题, 让我想起足球赛中的控球时间. 比如A队控球60%, B队40%, 好象A队厉害. 其实, A队相对于B队多出了20%控球时间, 只是B队少控了10%(如果每队按平均来分配时间, 各50%). 这种比较与另外的比较, 如A买了6个苹果, B买了4个苹果, A比B多了几个, 是不一样的. 不同的地方就是, 一个是总和不变, 只是在内部分配上变化, 两者之间相对比较; 另一个是总和是无限的, 两者之间绝对的比较.