# Lesson: Solve Proportions

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### Lesson Objective

SWBAT identify if two ratios are a proportion. SWBAT solve for the variable in a proportion.

### Lesson Plan

 Element/Time Teacher Student expected response Do Now (8:30 – 8:40)/(10:00 –10:10) ·         Teacher walks around to greet students and check in with students about their do now and homework ·         Students complete 2 review/2 current unit problems independently HW Check ·         Teacher walks around to help/spot check student HW Students correct homework from board with problems shown.  Students will ask questions in order to review misunderstood questions Mental Math (8:40 – 8:50) /(10:10 – 10:20) ·         Teacher reads and reveals a series of 6 problems – helping students to think of strategies to help students solve the problems ·         Teacher pulls sticks (cold call) to have students answer the questions ·         Students answer questions mentally, if stick is called they can answer and explain their answer choice. Mini Lesson (8:50 – 9:25)/(10:20 – 10:55) Intro: ·         Yesterday we learned about ratios – what is a ratio? ·         A comparison between two things ·         Today we are going to be looking at something we call a proportion. ·         A proportion is just two ratios that are equal to each other. ·         One way to determine if two ratios are a proportion is to determine if their quotients are the same.   Since ratios can be written sometimes with fraction bars we can think of the problem as a division problem.  If both ratios have the same quotient then they are equivalent to each other and therefore form a proportion. ·         Another way to determine if something is a proportion is to cross multiply.  If both answers are the same – then the two ratios form a proportion.  This works because we are using a shortcut way to give both ratios the same denominator and to see if the also have the same numerator.  If both cross products are equal then the two ratios form a proportion.   Guided: ·         Have students determine if two ratios is a proportion – students should use both methods   Intro: ·         Great, sometimes we have to find the value of a missing number (variable) in a proportion.  To do this we will cross multiply. ·         Show example. ·         What do you notice about what I have written now (students should see that it is a one-step equation) ·         Yes, it leaves us a with a one-step multiplication problem which we are really good at now.  So now I just need to divide on both sides in order to find out the value of the missing number (variable) Guided: ·         Students will solve 2 proportions for the unknown. Independent: ·         Complete worksheet independently Closing: ·         What did we learn? ·         Why is important? ·         What are some common mistakes? What does successful work look like/sound like? Skills Time (9:35- 9:50) /(11:05-11:25) Evaluate expressions

### Lesson Resources

 Notes Solve Proportions 2,066 U8.L7.Finding.the.Unknown.Proportion.Word.Problems.docx 2,333