Fractions always specify how much of a unit amount (or reference amount) there is, just as all  nonnegative numbers do. We can think of fractions, and all nonnegative numbers, as the result of  measuring by a unit amount.  Attending closely to a fraction’s unit amount is critically important for (1) solving problems,  (2) explaining arithmetic with fractions, and (3) understanding that fractions are numbers in the  same way that 2 and 3 are numbers. You can use language that emphasizes how much of a unit  amount a fraction specifies.