原文如下：
If these students are given unconnected units (say, tiles of a constant
length) and asked to demonstrate how to measure a length, some of them almost
always place the units against the object being measured in such a way that
the first and last tiles are lined up flush with the end of the object
measured, leaving spaces among the units in between.
我的翻译如下：
如果学生使用不连续的单位为工具(例如等尺寸的磁砖)来丈量一段长度，
有些学生几乎总是把这些单位紧密排列成直线，对齐被丈量物的头尾，
.................(最后一句，怎么翻都怪怪的...)
请诸位先进帮帮忙~~感恩！