Lesson plan - Study Island



|Math Lesson: Algebraic Expressions |Grade Level: 8 |

|Lesson Summary: Students model relationships with variables and equations. Advanced learners use algebra to solve number puzzles, and struggling learners |

|translate words into algebraic expressions. |

|Lesson Objectives: |

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|The students will know that… |

|relationships can be modeled with variables and equations. |

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|The students will be able to… |

|model relationships with variables and expressions. |

|evaluate algebraic expressions using the order of operations. |

|Learning Styles Targeted: |

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|Visual |

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|Auditory |

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|Kinesthetic/Tactile |

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|Pre-Assessment: |

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|Have students calculate how much a person will make if he earns $12 per hour and works different number of hours each week, like 3, 4, 5, 15, 20, 34, and 40. |

|Whole-Class Instruction |

|Materials Needed: paper, writing utensils |

|Procedure: |

|Lesson Presentation: |

|A variable is an unknown. It represents a number. An algebraic expression is a mathematical phrase that can include numbers, variables, and operation symbols. Use |

|a table to list the data from the pre-assessment and then write the algebraic expression that represents the situation. |

|3 |

|3*12=36 |

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|4 |

|4*12=48 |

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|5 |

|5*12=60 |

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|15 |

|15*12=180 |

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|20 |

|20*12=240 |

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|x |

|x *12=12x |

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|Explain how to write an algebraic expression for each phrase. |

|eight more than x (x+8) |

|the product of 3 and y (3y) |

|three times a number plus 7 (3x+7) |

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|Discuss patterns and the importance of the order of evaluating expressions. For example, to evaluate the expression 2x + 42/ 2 for x = 1, 7, 13, 22, the first step|

|is to simplify the power, then multiply and divide from left to right, and then add. |

|x |

|2x + 42/2 |

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|1 |

|2*1+42/2 = 2*1+16/2 =2+16/ 2 = 2+8 = 10 |

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|7 |

|2*7+42/2 = 2*7+16/2 =14+16/2 = 14+8 = 22 |

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|13 |

|2*13+42/2= 2*13+16/2 = 26+16/2 = 26+8=34 |

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|22 |

|2*22+42/2 = 2*22+16/2 =44+16/2 = 44+8 = 52 |

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|Evaluate the expression 4x - 23+ 30/y for x = 7 and y = 5. The first step is to substitute 7 for x and 5 for y. Simplify the power. Then multiply and divide from |

|left to right. Then add and subtract from left to right. 4(7) – 8 + 30/5 = 28 – 8 + 6 = 20 + 6 = 26 |

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|Guided Practice: |

|Help students write word problems that can be expressed with one variable. Brainstorm ideas as a class and then have students write an equation from the word |

|problem. For example, John goes to the store and buys 3 pounds of grapes for $5.67. How much does each pound of grapes cost? The equation would be 3x = $5.67 and |

|the answer would be x = $1.89 or one pound of grapes cost $1.89. |

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|Independent Practice: |

|Have students translate specific English phrases into algebraic expressions. |

|the total cost of n cases of water at 3.99 per case |

|the perimeter of a square where s is the length of a side |

|the number of slices of pizza if n pizzas are ordered and each pizza contains 8 slices |

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|Closing Activity: |

|Separate students into pairs. On index cards, have each student 1) write a word problem that can be expressed with one variable and 2) an algebraic expression to |

|be evaluated. Then students should exchange cards and translate the word problem into an algebraic expression and evaluate the algebraic expression. |

|Advanced Learner |

|Materials Needed: paper, writing utensils |

|Procedure: |

|Ask students to think of a number from 1 to 20. Multiply it by 4. Add 7 to it. Subtract 3. Divide by 4. Now subtract the original number. Have students compare |

|their results. Ask students if the result will be the same every time. |

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|Ask students to think of a number between 1 and 100. Multiply it by 3. Add 10 to it. Subtract 7. Divide by 3. Ask students “What is the result?” Based on the |

|result, tell student what the original number was. (result minus 1) |

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|Write an algebraic expression for each of these examples. Explain how the order of operations allows you to find the result every time. |

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|Ask students write an algebraic expression and then write the steps that describe each stage. |

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|Remind students that any time you end up with the same result it is due to multiplication being undone by division and addition being undone by subtraction. |

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|Have students write a series of steps that will allow them to guess what number their pattern started with. Example: One student asks another to think of a number,|

|multiply it by 2, and add 3. Multiply by 5. Then asks, “What is the result?” Based on the result, the student will be able to tell the other what his/her original |

|number was. |

|Struggling Learner |

|Materials Needed: PowerPoint Presentation*, paper, writing utensils |

|Procedure: |

|Review the order of operations and the words associated with each operation. |

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|Have students complete the questions on the PowerPoint presentation. Be sure that students can translate the English words into algebraic expressions. Have |

|students share what types of errors they made. |

*see supplemental resources

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