F

face

A flat side of a three-dimensional (3-D) shape.

fact family

Four related facts: two addition and two subtraction number sentences made using the same three numbers. For example, using 3, 4, and 7 the fact family is: 3 + 4 = 7; 4 + 3 = 7; 7 − 3 = 4; 7 − 4 = 3.

fair share

Splitting into equal groups or parts. For example, if there are 4 children and 12 cookies, each child's "fair share" is 3 cookies.

fixed variable

The variable in an experiment that does not change and keeps everything "fair." It is also called a controlled variable.

fourths

Four parts of a whole that are the same size. (See also fair share and one-fourth.)

fraction

Part of a whole in which all parts are equal or "fair shares." For example, the fraction is one of 4 equal parts. (See also equal parts and fair share.)