Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM 6•4 Lesson 10: Writing and Expanding Multiplication Expressions Student Outcomes ๏ง Students identify parts of an expression using mathematical terms for multiplication. They view one or more parts of an expression as a single entity. Classwork Discussion (4 minutes) ๏ง When we want to show multiplication of two numbers, like 5 and 7, we typically write 5 × 7, using the “×” to show the operation. When we start to use variables with multiplication, we can use other forms. ๐×๐ ๐โ๐ ๐๐ (๐)(๐) ๏ง Why might we want to use a form other than the × when variables are involved? ๏บ ๏ง The × can be confused for a variable instead of a symbol for an operation. Which of the three models can be used to show multiplication where there are no variables involved? ๏บ 5 × 7, 5 โ 7, and (5)(7), but not 57 because it looks like the number fifty-seven and not five times seven. Example 1 (10 minutes) MP.7 ๏ง When writing expressions using the fewest number of symbols, we have to refrain from using the symbols ×, โ, or ( ). ๏ง We will also be using math terms to describe expressions and the parts of an expression. We will be using words like factor, product, quotient, coefficient, and term. ๏ง A term is a part of an expression that can be added to or subtracted from the rest of the expression. In the expression 7๐ + 8โ + 3, what are examples of terms? ๏บ ๏ง 7๐, 8โ, and 3 are all terms. A coefficient is a constant factor in a variable term. For example, in the term 4๐, 4 is the coefficient, and it is multiplied with ๐. Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 106 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. NYS COMMON CORE MATHEMATICS CURRICULUM Lesson 10 6•4 Example 1 Write each expression using the fewest number of symbols and characters. Use math terms to describe the expressions and parts of the expressions. ๐×๐ a. ๐๐; the ๐ is the coefficient and a factor, and the ๐ is the variable and a factor. We can call ๐๐ the product, and we can also call it a term. ๐โ๐โ๐ b. ๐๐๐; the ๐๐ is the coefficient and a factor, and the ๐ is the variable and a factor. We can call ๐๐๐ the product, and we can also call it a term. ๐×๐×๐×๐×๐ c. ๐๐๐; ๐ is the coefficient and a factor, ๐ and ๐ are both variables and factors, and ๐๐๐ is the product and also a term. ๏ง Variables always follow the numbers and should be written in alphabetical order. Apply this knowledge to the examples below. ๐×๐×๐×๐ d. ๐๐๐๐; ๐๐ is the coefficient and factor, ๐ and ๐ are the variables and factors, ๐๐๐๐ is the product and also a term. MP.7 ๏ง If it is helpful, you can gather the numbers together and the variables together. You can do this because of the commutative property of multiplication. ๏บ 5×3×๐×๐ ๐×๐×๐ e. ๐๐๐ or ๐๐; ๐ and ๐ are the variables and factors, ๐ is the coefficient and factor if it is included, and ๐๐ is the product and also a term. ๏ง What happens when you multiply by 1? ๏บ Multiplying by 1 is an example of the identity property. Any number times 1 is equal to that number. Therefore, we don’t always need to write the one because 1 × ๐๐ค = ๐๐ค. Example 2 (5 minutes) Example 2 To expand multiplication expressions, we will rewrite the expressions by including the “ โ ” back into the expressions. a. ๐๐ ๐โ๐ Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 107 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. NYS COMMON CORE MATHEMATICS CURRICULUM b. Lesson 10 6•4 ๐๐๐๐ ๐โ๐โ๐โ๐ c. ๐๐๐ ๐๐ โ ๐ or ๐ โ ๐ โ ๐ โ ๐ d. ๐๐ โ ๐ ๐โ๐โ๐ e. ๐๐ โ ๐๐ ๐ โ ๐ โ ๐ โ ๐ or ๐ โ ๐ โ ๐ โ ๐ โ ๐ Example 3 (5 minutes) Example 3 a. ๏ง Find the product of ๐๐ โ ๐๐. It may be easier to see how we will use the fewest number of symbols and characters by expanding the expression first. ๐โ๐โ๐โ๐ MP.7 ๏ง Now we can multiply the numbers and then multiply the variables. ๐โ๐โ๐โ๐ ๐๐๐๐ b. ๏ง Multiply ๐๐ ๐ โ ๐๐๐. Let’s start again by expanding the expression. Then, we can rewrite the expression by multiplying the numbers and then multiplying the variables. ๐โ๐ โ๐โ๐โ๐โ๐ ๐โ๐โ๐ โ๐โ๐โ๐ ๐๐๐ ๐๐๐ c. ๏ง Double the product of ๐๐ and ๐๐๐. We can start by finding the product of 6๐ฆ and 3๐๐. Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 108 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM 6•4 ๐โ๐โ๐โ๐โ๐ ๐โ๐โ๐โ๐โ๐ ๐๐๐๐๐ MP.7 ๏ง What does it mean to double something? ๏บ It means to multiply by 2. ๐ โ ๐๐๐๐๐ ๐๐๐๐๐ Exercises (14 minutes) Students match expressions on a BINGO board. Some of the expressions are simplified, and some are expanded. To save time, provide students with a BINGO board with some of the squares already filled in. Have the remaining answers written on a smart board, a chalkboard, or an overhead projector so that students can randomly place them on the BINGO board. If there is not enough time for the BINGO game, these questions can be used on white boards, chalkboards, or some form of personal boards. Here are the clues to be given during the game, followed by the answers that are on the board. Questions/Clues Answers 10๐ 2โ5โm 8โ3โ๐ 24๐ Has a coefficient of 11 11๐๐ 14๐๐ 2โ7โ๐โ๐ (3๐)(9๐) 27๐๐ 11๐ โ 2๐ 22๐๐ 36๐ 2โ2โ3โ3โ๐ 2โ2โ2โ5โ๐ 40๐ 7๐๐ โ 5๐ก 35๐๐๐ก 18๐๐ก 2โ3โ3โ๐โ๐ก 7โ2โ๐กโ2โ๐ 28๐๐ก Has a coefficient of 5 5๐๐๐ก 3โ3โ5โ๐โ๐ 45๐๐ 5๐ โ 9๐๐ก 45๐๐๐ก 10๐๐ โ 4๐ก 40๐๐๐ก 1๐๐๐ก ๐๐๐ก 45๐๐ 3โ3โ5โ๐โ๐ (4๐๐)(11) 44๐๐ 54๐๐๐ก 3โ3โ3โ2โ๐โ๐โ๐ก Has a coefficient of 3 3๐ Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 These answers have already been included on premade BINGO boards to save time. The other answers can be randomly placed in the remaining spaces. 109 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM 2โ2โ2โ3โ๐โ๐ 24๐๐ (5๐)(3๐)(2๐ก) 30๐๐๐ก 13๐๐ (1๐๐)(13) Has a coefficient of 2 2๐ 6•4 Closing (3 minutes) ๏ง What is the difference between standard form and expanded form? ๏บ ๏ง When we write an expression in standard form, we get rid of the operation symbol or symbols for multiplication, and we write the factors next to each other. Sometimes we might have to multiply numbers together before writing it next to the variable or variables. When we write an expression in expanded form, we write the expression as a product of the factors using the “ โ ” symbol for multiplication. How would you describe the following terms? 1. Factor ๏บ A number or variable that is multiplied to get a product Variable ๏บ A letter used to represent a number Product ๏บ The solution when two factors are multiplied Coefficient ๏บ The numerical factor that multiplies the variable Lesson Summary AN EXPRESSION IN EXPANDED FORM: An expression that is written as sums (and/or differences) of products whose factors are numbers, variables, or variables raised to whole number powers is said to be in expanded form. A single number, variable, or a single product of numbers and/or variables is also considered to be in expanded form. Note: Each summand of an expression in expanded form is called a term, and the number found by multiplying just the AN EXPRESSION IN STANDARD FORM: An expression that is in expanded form where all numbers in a term together is called the coefficient of the term. After the word term is defined, students can be shown like-terms have been collected is said to be in standard form. what it means to “collect like terms” using the distributive property. Expressions in expanded form are analogous to polynomial expressions that are written as a sum of monomials. There are two reasons for introducing this term instead of the word polynomial: (1) In the Common Core State Standards, the word polynomial cannot be formally defined before high school, but the idea behind the word is needed much sooner. (2) The progressions are very clear about not asking problems that state, “Simplify.” However, they do describe standard form in the progressions, so students may be asked to put their answers in standard form. To get to standard form, students are asked to expand the expression and then collect like terms. Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 110 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. NYS COMMON CORE MATHEMATICS CURRICULUM Lesson 10 6•4 AN EXPRESSION IN STANDARD FORM: An expression that is in expanded form where all like terms have been collected is said to be in standard form. Note: Students cannot be asked to “simplify,” but they can be asked to “put an expression in standard form” or “expand the expression and collect all like terms.” Exit Ticket (4 minutes) Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 111 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM Name 6•4 Date Lesson 10: Writing and Expanding Multiplication Expressions Exit Ticket 1. 2. Rewrite the expression in standard form (use the fewest number of symbols and characters possible). a. 5๐ โ 7โ b. 3โ4โ5โ๐โ๐ Name the parts of the expression. Then, write it in expanded form. a. 14๐ b. 30๐๐ Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 112 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM 6•4 Exit Ticket Sample Solutions 1. Rewrite the expression in standard form (use the fewest number of symbols and characters possible). a. ๐๐ โ ๐๐ ๐๐๐๐ b. ๐โ๐โ๐โ๐โ๐ ๐๐๐๐ 2. Name the parts of the expression. Then, write it in expanded form. a. ๐๐๐ ๐๐ โ ๐ or ๐ โ ๐ โ ๐ ๐๐ is the coefficient, ๐ is the variable, and ๐๐๐ is a term and the product of ๐๐ × ๐. b. ๐๐๐๐ ๐๐ โ ๐ โ ๐ or ๐ โ ๐ โ ๐ โ ๐ โ ๐ ๐๐ is the coefficient, ๐ and ๐ are the variables, and ๐๐๐๐ is a term and the product of ๐๐ โ ๐ โ ๐. Problem Set Sample Solutions 1. Rewrite the expression in standard form (use the fewest number of symbols and characters possible). a. ๐โ๐ ๐๐ b. ๐โ๐ โ๐ ๐๐ ๐ c. ๐โ๐โ๐โ๐โ๐ ๐๐๐๐ d. ๐โ๐โ๐โ๐โ๐ ๐๐๐ 2. Write the following expressions in expanded form. a. ๐๐ ๐โ๐ b. ๐๐๐๐ ๐๐ โ ๐ โ ๐ Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 113 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. NYS COMMON CORE MATHEMATICS CURRICULUM c. Lesson 10 6•4 ๐๐๐๐ ๐๐ โ ๐ โ ๐ or ๐ โ ๐ โ ๐ โ ๐ โ ๐ d. ๐๐๐๐๐ ๐๐ โ ๐ โ ๐ โ ๐ or ๐ โ ๐ โ ๐ โ ๐ โ ๐ 3. Find the product. a. ๐๐ โ ๐๐ ๐๐๐ ๐ b. ๐๐๐๐ โ ๐๐๐ ๐๐๐๐๐๐ Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 114 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. NYS COMMON CORE MATHEMATICS CURRICULUM Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 Lesson 10 6•4 115 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM 2โ5โ๐ 6•4 35๐๐๐ก 45๐๐ 40๐ 24๐ 2โ7โ๐โ๐ 11๐๐ 28๐๐ก 22๐๐ 27๐๐ 5๐๐๐ก Lesson 10: 2โ3โ3โ๐โ๐ก Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 2โ2โ3โ3โ๐ 45๐๐๐ก 116 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM 22๐๐ 40๐ 28๐๐ก 2โ5โ๐ 45๐๐ 24๐ 2โ7โ๐โ๐ 6•4 5๐๐๐ก Lesson 10: Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 2โ2โ3โ3โ๐ 35๐๐๐ก 45๐๐๐ก 27๐๐ 11๐๐ 2โ3โ3โ๐โ๐ก 117 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Lesson 10 NYS COMMON CORE MATHEMATICS CURRICULUM 45๐๐ 40๐ 2 โ 3 โ 3 โ ๐ โ๐ก 5๐๐๐ก 24๐ 22๐๐ 11๐๐ 45๐๐๐ก 27๐๐ Writing and Expanding Multiplication Expressions This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from G6-M4-TE-1.3.0-09.2015 2 โ 2 โ3 โ 3 โ ๐ 28๐๐ก 2โ7โ๐โ๐ 2โ5โ๐ Lesson 10: 6•4 35๐๐๐ก 118 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.