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  
1,819
U8.L7.Finding.the.Unknown.Proportion.Word.Problems.docx  
1,810

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