The following comments were written for a review of a textbook for Math Concepts for Elementary Teachers.  The chapter in question was on measurement and conversions of units.  The comments on metric and English systems are broadly applicable in Math Education.

--Dr. Dwight Galster

This chapter is so important for elementary teachers, and our students have way too much trouble with this topic.  It’s really sad, but we are definitely seeing students come out of the high schools with very poor measurement calculation skills.  We need to work hard on this chapter.   I would like to see a lot more exercises on calculating perimeters, areas and volumes.  For conversions, I would like to see a lot more on converting between metric and English systems.  Volume, mass, and temperature seem to get short shrift by being lumped together in one section at the end.  Also, there should be more historical information about older units of measurement that we may not use often but appear in literature and in isolated practical applications.  I’m thinking of things like rods, hands, pecks, leagues and nautical miles, for example.  People should be aware of these measurements even though they may not need to be fluent in their use.  I also object to the pro-metric bias that is displayed in this book.  For example, there is a question on what the advantages of switching to the metric system are.  There is no corresponding question on what the advantages of the English system are.  The implication is that there are none, and that is blatantly false.  There are many good reasons for maintaining the English system.  In fact, it is completely impractical in some contexts to change over.  For example, the land in most of the country is now laid out in sections (square miles) and their regular subdivisions.  If you convert to metric hectares, all the plots would be in awkward, odd amounts.  All the roads, many of which are now one or two miles apart and mostly parallel, would become odd distances of kilometers apart.  It’s just not practical.  Even in Canada, which is supposedly a metric country (the book says the USA is the only major nation not to make the switch), the English system of measurements is still used in the construction industry.  It’s just not practical to switch the building of houses, which has been developed around 4x8 foot sheets and other regular English measurements, to metric units which would give awkward numbers.  A 4x8 ft sheet of plywood is approximately 1.22x2.44 meters.  And where do the studs go?  40.64 centimeters (16 inches) on center.  Who wants to work with numbers like that on a construction site?  And how much is 1/3 of a meter?  Compare that with 1/3 of a yard (12 inches) or 1/3 of a 4-ft sheet (16 inches).  We could change our standards, or customs, so that we could build with 1x3 m or 1x2.5 m sheets.  But doing so involves modifying not only blueprints, but a huge body of building codes that specify acceptable dimensions for safe and reliable building.  It is an impossible task.  The elimination of the English system is a pipe dream.  The failure of our math educators to appreciate this fact is unfortunate, because it leaves our students less prepared to deal with the real world.  Most of my students have never even considered that there is something good about the English system until I point out to them both the impossibility of changing everything over and the convenience of using numbers that are easily divided in many different ways.