Students will learn that a fraction, such as \(4/7,\) is equal to \(4 \cdot (1/7).\) That is, \(4/7\) can be thought of as \(4\) pieces of size \(1/7.\) Then students will learn how to use this idea to multiply whole numbers by fractions. For example, \((3/7) \cdot 2\) is \(3\) pieces of size \(1/7,\) times \(2,\) which is \(6\) pieces of size \(1/7,\) which is \(6/7.\) Some problems will be expressed as \(2/3 \cdot 4,\) while others will be expressed as \(2/3\) of \(4.\) Of course, these are equivalent.
How to Find a Fraction of a Whole Number by Math by Math with Mr. J
Solve word problems involving multiplication of a fraction by a whole number. Start with manipulatives and pictures, then gradually move away from them.
Do these Khan Academy exercises:
- Interpret multiplying fraction and whole number word problems
- Multiply mixed numbers and whole numbers
- Multiply fractions and whole numbers with fraction models
- Multiply fractions and whole numbers
- Multiply unit fractions and whole numbers
- Equivalent whole number and fraction multiplication expressions
- Multiply fractions and whole numbers on the number line
Conclude by leading this investigation:
Lazy Toad Puzzles (counting, symmetry)
4.NF.B.4: Apply and extend previous understandings of multiplication to multiply a fraction by a whole number.