Quoting from the Town of Brookline’s newly chosen math textbook for sixth grade:
1 is to 1.67 as 6 is to 10
b/g = b/(b+g) [this in a situation where b is nonzero]
Two figures that have the same shape are similar.
Figures that have the same size and shape are congruent.
Perimeter: The distance around a two-dimensional shape.
Percent [one word; used as a noun]
The exact value of pi is a decimal number whose digits never end or repeat.
— Impact Mathematics, Glencoe McGraw-Hill, 2009