为什么教室里的"黑板"变成绿色了?很多人都没想到-科普中国蟒缘
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以前上初中的时候
坐在教室听课时
就在想一个问题
为什么老师总是说请看黑板
但是那块板却是绿色的?
难道其中有某些误会?
其实,19世纪初人们用大块的石板
连接起来做成了黑板
让教师能够在上面写字给全班看
而“黑板”这个名字是在1815年才出现的
在18世纪的时候
因为纸和墨比较昂贵
所以便宜耐用的可擦写石板
便成为了代替品
当时学生上课的时候
会自备一块黑色的石板来上课
这些“小黑板”就是课室里大型黑板的前身
因此最初的时候
黑板的确是全都黑色的
当时的黑板是用石板做成的
而在农村地区
黑板的原材料是木板
人们将蛋清和烤焦的土豆混在一起
将木板涂成深色的
后来黑板则全都是用木板做的
那时候的黑板
才是不掺假的“黑板”
到了20世纪,黑板开始接受整容了
对整天盯着黑板的教师们来说
绿色黑板颜色更加柔和对眼睛更加友好
于是“真·黑板”们
逐渐被绿色的黑板取代了
天桥演艺
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来源:好奇实验室(ID:haoqishiyanshi)
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