ABSTRACT
This chapter discusses common mistakes in math instruction and explains the misunderstandings behind them. It was time to take up the topic on nonstandard measurement, and Jane started off with telling her children the rationale for it. It's true that people sometimes do use concrete objects as makeshift tools for measuring other objects. But the rationale for teaching nonstandard measurement in an elementary school classroom is not for addressing the unavailability of measuring tools. It is interesting to note that some people use term standard measurement in nonstandard ways. Currently two systems of measurement are in use worldwide: the metric system and customary system. Nonstandard measurement refers to the use of common objects such as pencils, paper clips, and even body parts such as hands and arms, in measuring some other objects. In teaching how to measure length in metric units, Jane displayed part of a ruler marked in centimeters, with each one further divided into 10 smaller units.
