# Using Graphic Organizer to Calculate Tips

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## Objective

SWBAT use a graphic organizer to organize their thinking in order to calculate tips applied to restaurant bills.

#### Big Idea

Calculating tips is a very important skill. Knowing how to calculate a tip at a restaurant quickly and precisely is a good skill to have. Let's sharpen our skills.

## Pre-Lesson Guided Notes

Pre-Lesson Teacher Guided Notes: In order for students to successfully calculate tips, students will need a strong number sense background.  Students will convert percentages to decimals, estimate to the nearest hundredth place, multiply decimals, add decimals, and identify values of decimals. Students should use their knowledge gained from 6.NS.B.3 to help calculate the tips and increased amount. In future lessons, we will learn to model the steps using bar diagrams, and tables to calculate tips.

It is important in future lessons to tie in real world scenarios so that students have an understanding of the importance of tipping, who should be tipped, and the appropriate amount to tip. Some students may not have a clear understanding how to calculate tips.  This lesson will ask for students not only to calculate tips from a percentage, but also calculate a percentage from an amount given.  This lesson will be similar in the sales tax lesson.  Students will use the same processes to find the tip.  In the next day lesson we will dive deep into the reasons why we tip, who we tip, the appropriate amount to tip, what happens when we do not tip, and calculate different tip amounts, and final cost amounts.  In this particular lesson we will focus on calculating the tip and final cost using the graphic organizer to help organize thinking.

## Opening Discussion

5 minutes

Opener : Whole group Discussion

Open this lesson with a whole group discussion from the previous day’s lesson over calculating discount.  Discuss the strategies students used.  Address common mistakes made.  One main common mistake students make is subtracting the percentage, and not finding the discount.  One other common mistake for students to make is finding the discount and using this as the sale price.  Discuss how using the graphic organizer enabled them to organize their thinking in order to solve for the discount and find the sale price.  Students should have kept note over the mistakes that they made.  Allow the students to discuss these mistakes, and double check for that the closing of the day’s lesson enabled them to gain the understanding they needed.

## Bell Ringer

20 minutes

Bell Ringer:  Hand each student the bell ringer as they enter the room. Students will begin the bell ringer after you have the whole group discussion. Have students work on the problem individually for 10 minutes.  Students will use mathematical practice 1, 2, 4 and 6. My students have assigned seats for their I.T.T seats, once again this is their Individual Think Time seats.  Students will grapple with the problem for 10 minutes on their own.  During this time students may use a variety of strategies to calculate the tip.  By this point in the unit, students will begin to see similarities between discount, tax and now tip.  Students will exercise MP 8.

If you notice students discovering connections between the procedures, remind them that they are using MP 8.  Students should explain their thinking, record their work, and articulate the strategy they chose in order to solve the problem.   Wait to give your students the graphic organizer until the student activity.  At this time in the unit, the students who will need the graphic organizer are students who still struggle with understanding of calculating discounts and tax.  After students have had the opportunity to organize their thoughts, think quantitatively, and/or abstractly, try different methods, reorganize their thoughts, and attempt to solve the problem with accuracy, allow the students to pair up with another student or group of students to compare their thinking and results.   Students will be in P.U.T seats.  This is pair up time.

Students will use MP 3 during this time.  Students should defend their thinking with their peers, critique the work of others, and correct mistakes as a result of the mathematical discussions.  Allow students 10 minutes during P.U.T. During this time while you walk the room checking for understanding you are looking for students who are able to calculate the tips and final cost. Students who have little to no understanding will attempt to solve the problem by adding the percent to the original cost. The graphic organizer will help with this misconception.  For those students who do not need the graphic organizer, have them move forward with completing the student activity task without the graphic organizer. For the students who continue to struggle, use the opening discussion to help guide student thinking.   Students should use their understanding of discounts, and tax toward the understanding of calculating tip.  It is often underestimated the power of isolating discount meaning an amount off, and tax an amount added.  You may also use this thinking toward calculating tips.

Ask students, if you conducted a service for someone, and you charged them \$20.00, but the person tipped you \$5.00, what does this mean?

Will you have more than \$20.00, if so why?

Which mathematical operation did you use?

The meat of the discussion will be for students to understand what the percent means, what is the relationship of the percent to the original cost?

Students should also understand that finding the tip is different than finding the new cost.  The tip is the amount added to the original cost, the new cost is the price after the tip is added.

I would start student thinking with placing them in a personal situation.  The majority of your students should have experienced a situation in which there was a tip given, or a tip received.  Ask them to share their experience.  What was the service?  What was the tip?  Which mathematical operations are involved in finding the tip when the tip is expressed in a percent?

## Student Activity

10 minutes

Student Activity:  After students have had the opportunity to grapple through the problem, give them the graphic organizer.  Allow students to use their work accomplished during the bell ringer and adjust thinking using the graphic organizer.  Allow students 10 minutes to use the graphic organizer.  During this time assess if the graphic organizer reorganizes student thinking.  The graphic organizer will help students who have little understanding gain starting points, isolate the stages of the process, and help students build understanding of the process in order to build other strategies to calculate tip and final cost. For those students who do not need the graphic organizer, give them problems to solve while the other students use the graphic organizer to help them understand the process in calculating tips and final cost.

## Closing

5 minutes

Closing: For this closing take 5 minutes to discuss calculating tips and final cost. During the whole group discussion compare the graphic organizers and the processes from all of them.  Talk about the difference in discount, tax and tip.  Discuss ways in which discounts will be taken.  Students should identify, percentages off, amounts off, and even a combination of both.  Where do we encounter discounts?  What time of the year are discounts (sales) most prevalent?  Why?  Does this help sales?  Will the sales tax increase during this time?  Why or why not?  Will people tip more during this time?  Why or why not?  In this closing, use your Smartboard, document camera, white board, or chalk board to go over the graphic organizer.  Have students check their work as you go over each step of the graphic organizer.  If students make mistakes, encourage them to correct their mistakes, and also keep note of the mistakes they made.