Common Core Math 5.nf.4a
Number And Operations - Fractions: Apply And Extend Previous Understandings Of Multiplication And Division To Multiply And Divide Fractions.
Interpret the product (a/b) x q as a parts of a partition of q into b equal parts; equivalently, as the result of a sequence of operations a x q / b. For example, use a visual fraction model to show (2/3) x 4 = 8/3, and create a story context for this equation. Do the same with (2/3) x (4/5) = 8/15. (In general, (a/b) x (c/d) = ac/bd.)