People appear to be born to compute. The numerical skills of children develop so early and so inexorably that it is easy to imagine an internal clock of mathematical maturity guiding their growth. Not long after learning to walk and talk, they can set the table with impressive accuracy -- one knife, one spoon, one fork, for each of the five chairs. Soon they are capable of noting that they have placed five knives, spoons and forks on the table and, a bit later, that this amounts to fifteen pieces of silverware. Having thus mastered addition, they move on to subtraction. It seems almost reasonable to expect that if a child were secluded on a desert island at birth and retrieved seven years later, he or she could enter a second-grade mathematics class without any serious problems of intellectual adjustment. Of course, the truth is not so simple. This century, the work of cognitive psychologists has illuminated the subtle forms of daily learning on which intellectual progress depends. Children were observed as they slowly grasped -- or, as the case might be, bumped into -- concepts that adults take for granted, as they refused, for instance, to concede that quantity is unchanged as water pours from a short stout glass into a tall thin one. Psychologists have since demonstrated that young children, asked to count the pencils in a pile, readily report the number of blue or red pencils, but must be coaxed into finding the total. Such studies have suggested that the rudiments of mathematics are mastered gradually, and with effort. They have also suggested that the very concept of abstract numbers - the idea of a oneness, a twoness, a threeness that applies to any class of objects and is a prerequisite for doing anything more mathematically demanding than setting a table - is itself far from innate.
【加练半小时】2017届高考英语一轮复习练习:第19练 健康与医疗类(一)(含解析)
【加练半小时】2017届高考英语一轮复习练习:第11练 人物传记类(二)(含解析)
2017版高考一轮复习课件:选修7 unit19《Language》(北师大版)
2017版高考一轮复习课件:选修8 unit23《Conflict》(北师大版)
2017版高考一轮复习课件:选修6 unit16《Stories》(北师大版)
2017版高考一轮复习课件:必修5 unit13《People》(北师大版)
【加练半小时】2017届高考英语一轮复习练习:第20练 健康与医疗类(二)(含解析)
2017版高考一轮复习课件:选修7 unit20《New Frontiers》(北师大版)
【高考调研】2017届高三英语一轮复习(外研版)课时规范训练1(含解析)
【加练半小时】2017届高考英语一轮复习练习:第18练 饮食类(含解析)
Banana skin?
中国发布《网络空间国际合作战略》
【加练半小时】2017届高考英语一轮复习练习:第14练 旅游与交通(二)(含解析)
2017版高考一轮复习课件:选修6 unit17《Laughter》(北师大版)
【加练半小时】2017届高考英语一轮复习练习:第15练 自然与环保类(一)(含解析)
【加练半小时】2017届高考英语一轮复习练习:第8练 语言学习类(一)(含解析)
2017版高考一轮复习课件:必修5 unit15《Learning》(北师大版)
【高考调研】2017届高三英语一轮复习(外研版)课时规范训练4(含解析)
2017版高考一轮复习课件:必修1 unit2《Heroes》(北师大版)
2017版高考一轮复习课件:选修6 unit18《Beauty》(北师大版)
【加练半小时】2017届高考英语一轮复习练习:第16练 自然与环保类(二)(含解析)
【加练半小时】2017届高考英语一轮复习练习:第22练 体育类(含解析)
2017版高考一轮复习课件:必修4 unit12《Culture shock》(北师大版)
【加练半小时】2017届高考英语一轮复习练习:第6练 人际关系类(一)(含解析)
【高考调研】2017届高三英语一轮复习(外研版)课时规范训练3(含解析)
【加练半小时】2017届高考英语一轮复习练习:第7练 人际关系类(二)(含解析)
【加练半小时】2017届高考英语一轮复习练习:第23练 文化习俗类(含解析)
【加练半小时】2017届高考英语一轮复习练习:第17练 自然与环保类(三)(含解析)
【加练半小时】2017届高考英语一轮复习练习:第13练 旅游与交通(一)(含解析)
2017版高考一轮复习课件:必修2 unit5《Rhythm》(北师大版)
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