Apples and Oranges in Teaching The Use of Units
While references to comparing apples and oranges is often a rhetorical device, references to adding apples and oranges are made in the case of teaching students the proper uses of units. Here, the admonition not to "add apples and oranges" refers to the requirement that two quantities with different units may not be combined by addition, although may always be combined by multiplication, so that multiplying apples and oranges is allowed. Similarly, the concept of this distinction is often used metaphorically in elementary algebra.
The admonition is really more of a mnemonic, since in general counts of objects have no intrinsic unit and, for example, a number count of apples may be dimensionless or have dimension fruit; in either of these two cases, apples and oranges may indeed be added.
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Famous quotes containing the words apples, oranges, teaching and/or units:
“According to legend, Dr. Sappington purchased his coffin several years before his death and kept it under his bed, with apples and nuts in it for his visiting grandchildren.”
—Administration in the State of Miss, U.S. public relief program (1935-1943)
“I don’t give a hoot in a hollow if there’s oranges and grapes a-crowdin’ us out of bed, I ain’t goin’ to California! This is my country and I belong here. This is my dirt. It’s no good, but it’s mine.”
—Nunnally Johnson (1897–1977)
“Teaching creativity to your child isn’t like teaching good manners. No one can paint a masterpiece by bowing to another person’s precepts about elbows on the table.”
—Gurney Williams III (20th century)
“Even in harmonious families there is this double life: the group life, which is the one we can observe in our neighbour’s household, and, underneath, another—secret and passionate and intense—which is the real life that stamps the faces and gives character to the voices of our friends. Always in his mind each member of these social units is escaping, running away, trying to break the net which circumstances and his own affections have woven about him.”
—Willa Cather (1873–1947)