Standard 4.NF.4 – Multiplying Fractions by whole numbers

Standard 4.NF.4 
Apply and extend previous understandings of multiplication to multiply a fraction by a whole number.

A. 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). 

B. Understand a multiple of a/b as a multiple of 1/b, and use this understanding to multiply a fraction by a whole number. For example, use a visual fraction model to express 3 x (2/5) as 6 x (1/5), recognizing this product as 6/5. (In general, n x (a/b) = (n x a)/b). 

C. Solve word problems involving multiplication of a fraction by a whole number (for example, by using visual fraction models and equations to represent the problem). For example, if each person at a party will eat 3/8 of a pound of roast beef, and there will be five people at the party, how many pounds of roast beef will be needed? Between what two whole numbers does your answer lie? 

Explanation: We really are just multiplying fractions by whole numbers, in different ways. Students need to understand that 5X1/8 is 5/8. (Because 1/8 + 1/8 + 1/8 + 1/8 + 1/8 = 5/8.)  Look at the videos below for more clarification.


Class Video: