Unit Rate Problems (Part 3 of 3)

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SWBAT find equivalent ratios by determining and applying the unit rate

Big Idea

If we know the unit rate of a ratio relationship, we can find any equivalent ratio easily with any whole number value.

Think About It and Guided Practice

20 minutes

As they arrive, students begin to work independently on the Think About It  problem.  Students are able to successfully complete the Think About It problem using either a double number line or a ratio table. After 2 minutes of work time, I ask for a student to display his/her work on the document camera.  The student walks through how (s)he solved the problem.  I then ask the class for feedback on the model and work shown.

Because this is the third (and final) lesson on unit rate, there is not direct instruction or new material in this lesson.  After the Think About It problem, I ask students to help me answer the questions about unit rate. 

I then have students independently complete the example problem.  After 2 minutes of work time, I cold call on a student to show his/her work on the document camera.  Much like with the Think About It Problem, the student walks through how (s)he solved the problem.  I then ask the class for feedback on the model and work shown.


Partner Practice and Discussion

18 minutes

Students will work in pairs on the Partner Practice problem set.  As they work, I circulate around the classroom.  I am looking for: 

  • Are students explaining their thinking to their partner?
  • Are students writing their work in the work space?
  • Are students drawing the chosen model correctly?
  • Are students using their models to answer basic questions?

 I am asking:

  • How did finding unit rate help you solve this problem? 

Students may pick between two models as they work.  I am looking to be sure that their work looks like the following samples:  double number line and ratio table.

After partner practice, students complete the check for understanding question.  I have students clap out their answer choice.  Then, a student shares his/her model on the document camera. Check out the Check For Understanding sample. 


Independent Practice

20 minutes

Students work on their own on the Independent Practice problem set.

In the first problem of this set, students are asked to find the cost of a pound of corn.  One thing I look for as students work is whether or not students are making sense of this problem.  Occasionally, a student will create a ratio table and find the unit rate.  That student will then use a scale factor of one in the table (so the table shows corn:$ as 5:7, 1:1.40, and then another 1:1.40)  When I see this, I know that students are not reading the problem and really understanding what the problem is asking them to find.   

The Challenge Questions in this section require students to work more with decimals and fractions, and are good extension problems for more advanced students.  

Closing and Exit Ticket

7 minutes

Students work independently on the Exit Ticket to close this lesson.  An Exit Ticket Sample is included, to show what student work could look like on these problems.  This student used ratio tables for both problems, but double number lines are appropriate models to use for solving either of these problems. 

Before students turn in their exit tickets, I have them turn and tell their partner how using unit rates helped them to find equivalent ratios in our unit rate lessons.