Lesson+1-4

CONCEPT: **LEAST COMMON DENOMINATOR AND GREATEST COMMON FACTORS** OBJECTIVE: Find the GCF of two or more numbers, and find the LCD of two ore more fractions with unlike denominators COMMON CORE: Mathematics » Grade 4 » Number & Operations—Fractions (4.N.F)

Extend understanding of fraction equivalence and ordering.
==Build fractions from unit fractions by applying and extending previous understandings of operations on whole numbers.==
 * 1. Explain why a fraction //a/////b// is equivalent to a fraction (//n// × //a//)/(//n// × //b//) by using visual fraction models, with attention to how the number and size of the parts differ even though the two fractions themselves are the same size. Use this principle to recognize and generate equivalent fractions.
 * 2. Compare two fractions with different numerators and different denominators, e.g., by creating common denominators or numerators, or by comparing to a benchmark fraction such as 1/2. Recognize that comparisons are valid only when the two fractions refer to the same whole. Record the results of comparisons with symbols >, =, or <, and justify the conclusions, e.g., by using a visual fraction model.
 * 3. Understand a fraction //a/////b// with //a// > 1 as a sum of fractions 1///b//.
 * Understand addition and subtraction of fractions as joining and separating parts referring to the same whole.
 * Decompose a fraction into a sum of fractions with the same denominator in more than one way, recording each decomposition by an equation. Justify decompositions, e.g., by using a visual fraction model. //Examples: 3/8 = 1/8 + 1/8 + 1/8 ; 3/8 = 1/8 + 2/8 ; 2 1/8 = 1 + 1 + 1/8 = 8/8 + 8/8 + 1/8.//
 * Add and subtract mixed numbers with like denominators, e.g., by replacing each mixed number with an equivalent fraction, and/or by using properties of operations and the relationship between addition and subtraction.
 * Solve word problems involving addition and subtraction of fractions referring to the same whole and having like denominators, e.g., by using visual fraction models and equations to represent the problem.
 * 4. Apply and extend previous understandings of multiplication to multiply a fraction by a whole number.
 * 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 × (1/4), recording the conclusion by the equation 5/4 = 5 × (1/4).//
 * 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 × (2/5) as 6 × (1/5), recognizing this product as 6/5. (In general, n × (a/b) = (n × a)/b.)//
 * Solve word problems involving multiplication of a fraction by a whole number, e.g., 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 5 people at the party, how many pounds of roast beef will be needed? Between what two whole numbers does your answer lie?//

Lesson 1.4-fractions.notebook