Common Core State Standards
CCSS.Math.Content.4.NF Number and Operations--Fractions
CCSS.Math.Content.4.NF.B Build fractions from unit fractions by applying and extending previous understandings of operations on whole numbers.
CCSS.Math.Content.4.NF.B.4 Apply and extend previous understandings of multiplication to multiply a fraction by a whole number.
CCSS.Math.Content.4.NF.B.4a Understand a fraction a/b as a multiple of 1/b. For example, use a visual fraction model to represent 5/4 as the product 5 x (1/4), recording the conclusion by the equation 5/4 = 5 x (1/4).