Percent: Using the Proportion Method Lesson Plan


Vocabulary: Ratio, Proportion, Part, Whole/Base, Percent/Rate, Cross-Multiply

Goals: Aims

1. Students will understand the concept of a percent as part of a whole.

2. Students will understand the given percent formula as a proportion.

3. Students will apply prior knowledge of solving a proportion problem to solving a percent problem: finding the part.


1. Students will be able to analyze and identify the three parts of a "find the part" percent number sentence.

2. Students will be able to analyze and identify the three parts of a "find the part" percent word problem.

3. Students will be able to substitute the correct values into the Percent Proportion Formula from given information in a percent number sentence and word problem.

4. Students will use the proportion method to solve for the part in a percent number sentence and a word problem.


Whiteboard, Proportion Method Graphic Organizer, Newspaper Ad, Steck Vaughn GED Math book, Pre-GED Math books


A. Introduction-

1. Write the % symbol on the board and ask students what it is, where they have seen the symbol, and how it is used in their lives.

2. Write their responses on the board.

3. Talk about the meaning of the word "Per Cent" as "a part out of a total of 100(%)" and make the connection between other words with the "cent" root: cents, century, centipede, centimeter.

4. Briefly review the connection between decimal, fraction, and percent in terms of hundredths: .25 = 25/100 = 25%.

5. Describe a percent as a ratio or fraction that is part/whole, with the whole as always being 100%.

B. Development-

1. Briefly review Ratios and Solving Proportions.

2. Explain to the class that the same Cross-Product Rule used to solve proportion problems can be used to solve percent problems. Hand out the Finding the Part Using the Proportion Method Graphic Organizer.

3. Explain the different parts of the Percent Number Sentence and how they fit into the Proportion Formula.

4. Demonstrate by solving the sample problems using the Cross-Product Rule with and without a calculator.

5. Ask students to solve the rest of the Number Sentence problems, in pairs if they choose, and monitor their work.

6. Review the answers and calculations together.

C. Practice-

1. Explain to the class that the Proportion Method can be used to find the part in GED Math Word Problems.

2. Demonstrate how to substitute values into the formula using information given in the sample word problem and solve the problem without a calculator.

3. Remind the class of the importance of checking your work and making sure that the answer is reasonable.

4. Demonstrate how to solve the next problem with the use of the calculator.

5. Ask students to complete the Lowes Ad word problem on their own and closely monitor their progress.

6. Review the answer and calculations together.

D. Independent Practice-

1. Assign the students to complete problems from Steck Vaughn GED Math, Lesson 12, page 139, Part A: 1-6, Part B: 13-16, and all of Part C.

E. Accommodations (Differentiated Instruction)-

1. For Pre-GED level students, assign Independent Practice from Steck Vaughn or Contemporary Pre-GED Math books or from Number Power M.

2. Allow students to complete the assignment at home if necessary.

3. Allow the full use of the calculator for those with that specific IEP Testing Accommodation.

4. Allow students to complete the assignment in pairs.

5. Be available for extra guidance and questions when needed.

F. Checking for understanding-

1. Ask for each student to come to the board to show to the class how they solved one of the Independent Practice problems.

2. Reward each student with praise and applause.

3. Collect completed work to check their calculations and answers.

G. Closure-

1. Ask students to go back to the Lowes Ad problems and ask them exactly how much they would pay for one of the refrigerators on sale and how they would figure that out.

2. Allow them time to discover what the next logical step would be (Subtraction of the Part from the Whole) to solve the extended problem.

3. When someone says that they need to subtract, ask the class to make the calculation. Review the calculation and correct answer on the board after they finish.

4. Tell students that we will be doing more multi-step percent problems like this one next class.


Determine the level of understanding based on results from calculations and answers on the Independent Practice.