In RS2 Level C, Lesson 109, the child is introduced to measuring area. After a problem of square inches is discussed, the lesson shows the child how to write 12 square inches: 12 in². Then, there’s an explanation on the side that reads:
Be sure to read 12 in² as “twelve square inches.” Avoid saying “twelve inches squared,” which has an entirely different meaning.
Kirsten sent us an email and wanted a more complete explanation of the different meaning of twelve inches squared. Good question, Kirsten!
Ok. I will confess I had to go to Dr. Cotter to clarify this for both of us! So here it is.
First, if you say “12 inches,” that’s easy. It’s just 12 inches!
It’s a measurement of area, indicated by the word “square” and the little ². The measurement for the area under discussion is inches. Hence the name “12 square inches,” written by “12 in².”
12² = 144
Extending that, if you say “12 inches squared,” it’s a logical process to square 12 inches, giving us 144 inches.
So “12 inches squared” is a long distance of 144 inches and “12 square inches” is a 3 by 4 inch area. Or 2 by 6. Or 1 by 12. You get my drift.