Back in 1922, Thomas Edison predicted that "the motion picture is destined¹ to revolutionize our educational system and...in a few years it will supplant² largely, if not entirely³, the use of textbooks." Well, we all make mistakes. But at least Edison did not squander⁴ vast quantities of public money on installing cinema screens in schools around the country.

1922年的时候，托马斯·爱迪生曾经预测说“电影必将革新我们的教育制度，…要不了几年，它就能取代大部分（即便不是全部的）教科书。”当然，人都会有出错的时候。不过至少在给全国各地的学校安装电影屏幕这件事上，爱迪生并没有浪费大笔公共资金。

With computers, the story has been different. Many governments have packed them into schools, convinced that their presence would improve the pace and efficiency of learning. Large numbers of studies, some more academically respectable than others, have purported⁵ to show that computers help children to learn. Now, however, a study that compares classes with computers against similar classes without them casts doubt on that view.

有了电脑，情况又不一样了。许多政府已经把电脑装进了学校，并深信电脑会提高学习的速度和效率。大量的研究，其中还包括一些学术性更强的研究，都试图说明电脑有助于儿童的学习。不过，现在有一项对用电脑教学和不用电脑教学的课堂的比较研究对这一观点提出了怀疑。

In the current Economic Journal, Joshua Angrist of the Massachusetts Institute of Technology and Victor Lavy of the Hebrew University of Jerusalem look at a scheme which put computers into many of Israel's primary and middle schools in the mid-1990s. Dr Angrist and Dr Lavy compare the test scores for maths and Hebrew achieved by children in the fourth and eighth grades (ie, aged⁶ about nine and 13) in schools with and without computers. They also asked the classes' teachers how they used various teaching materials, such as Xeroxed worksheets and, of course, computer programs. The researchers found that the Israeli scheme had much less effect on teaching methods in middle schools than in elementary schools. It also found no evidence that the use of computers improved children's test scores. In fact, it found the reverse. In the case of the maths scores of fourth-graders, there was a consistently negative relationship between computer use and test scores.

在本期经济专刊中，来自麻省理工学院的乔舒亚·安格里斯特和耶路撒冷希伯莱大学的维克多·拉维对九十年代中期开始在许多以色列中小学安装电脑的计划进行了研究。安格里斯特博士和拉维博士比较了有电脑和没有电脑的四年级和八年级（也就是年龄在9到13岁之间）的儿童在数学和希伯莱语两个科目的考试成绩。他们还访问了课堂教师，询问他们是如何使用各种教学材料，例如复印纸，电脑设备等。两位研究者发现，这个以色列计划在改进中学教学方法方面的效果比小学的效果逊色得多。研究还发现，没有证据证明使用电脑能够提高儿童的考试成绩。实际上，情况正好相反。从四年级学生的数学成绩来看，使用电脑和考试成绩的关系一直成反比。

The authors offer three possible explanations of why this might be. First, the introduction of computers into classrooms might have gobbled up cash that would otherwise have paid for other aspects of education. But that is unlikely in this case since the money for the programme came from the national lottery⁷, and the study found no significant change in teaching resources, methods or training in schools that acquired computers through the scheme.

两位作者对这种情况提出了三种可能的解释。第一，将电脑引入课堂可能会占用本应用于其它教育方面的资金。但在这个例子当中，这种情况不太可能发生，因为该计划的资金来自国家彩票。研究发现，在按照该计划添置电脑的学校中，教学资源，教学方法或者培训并没有显著变化。

A second possibility is that the transition to using computers in instruction takes time to have an effect. Maybe, say the authors, but the schools surveyed had been using the scheme's computers for a full school year. That was enough for the new computers to have had a large (and apparently⁸ malign) influence on fourth-grade maths scores. The third explanation is the simplest: that the use of computers in teaching is no better (and perhaps worse) than other teaching methods.

第二种可能性就是用电脑授课的这种变化要一段时间才能见效。两位作者说的只是一种可能性，但被调查的学校使用计划中的电脑已经有整整一学年了。新电脑在这段时间里足以对四年级的数学成绩产生较大的（但显然是不利的）影响。第三种解释也最简单：在教学中使用电脑并不比其他教学方法更好（也许还更糟）。

The bottom line, says Dr Angrist, is that "the costs are clear-cut and the benefits are murky⁹." The burden of proof now lies with the promoters of classroom computers. And the only reliable way to make their case is, surely, to conduct a proper study, with children randomly¹⁰ allocated¹¹ to teachers who use computers and teachers who use other methods, including the cheapest of all: chalk and talk.

最后，安格里斯特博士说：“成本很清楚，但收效却很模糊。”求证效果的担子现在就落在那些提倡在课堂使用电脑的人身上了。而他们所能采用的唯一可靠方法当然就是进行适当的研究，学生应该是随机分配给使用电脑教学的教师和使用其他方法教学的教师，包括最廉价的方法：粉笔和谈话。