Math textbook stupidity

Probably because American schools from K-12 through university level make use of many metric measurements all the time, so a familiarity with them only makes educational sense.

:smack: Damn poor calculator that doesn’t know an uncalculable problem. I stand corrected. :smack:

It has to do with the different types of numbers. From my statistician days I remember that there were nominal, ordinal, natural and cardinal (other categories are out there also). This is important to statisticians because it determines what kind of tests you can run on the data.

Nominal numbers are just numbers that are used as a name. In databases you might use 1 = Alabama, 2 = Alaska. 3 = Arkansas. You can’t do any arithmetic operations an nominal numbers, e.g., 2+3 != Florida.

Ordinal numbers show the order of something. In statistics you often group people’s income by ordinal numbers, e.g., 1 = $0 - $5,000, 2 = $5,000 - $10,000, etc. You know from the number whether one preson’s income is greater than another’s, but you can’t say by how much other than crude estimate.

Natural numbers, which is what temperatures are, can be added and subtracted but not multiplied or divided because there is no true zero. Zero degrees Celcius or Farenheit are arbitrary points on the thermometer. Even if you look at the Kelvin scale, I don’t think you can say that 100 K is twice as hot as 50 K.

Finally cardinal numbers (distance between point A and point B, weight, etc) can be added, subtracted, multiplied and divided.

This page has a lesson plan on this that appears to be directed at 4th - 6th graders.

Good explanation, bnorton, although FWIW the Stats textbook I’ve taught from calls 'em nominal, ordinal, interval, and ratio scales or levels of measurement. (The terms “natural numbers” and “cardinal numbers” are used to mean something different in math.)

I have been ranting incoherently about both of these, which frequently occur in the media, for years and nothing has been done about it. I suppose it would help if I ranted at someone other than my wife, who has little power to actually change the situation, but you use whatever target is available, I suppose.

Update that I’d forgotten to post for a while: remember that Monday or Tuesday that there was a huge cold snap a bit before Christmas? Dan Rather led off the news that night with, “Across a third of the nation, temperatures were half of what they were yesterday.”