More Tax, Tips, and Discounts

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SWBAT review concepts in tax, tip, discounts, and scale factors to improve mastery.

Big Idea

students watch a learnzillion video to review percent problems with bar models and review scale factor problems.

Do Now

10 minutes

Students enter silently according to the Daily Entrance Routine. A timer is set with 5 minutes and Do Now assignments are placed face-down on student desks. The directions on the board read:

Sit down quickly and silently. Take out a pencil. Write your name on the paper, but don’t turn it over! You have 5 minutes. Raise your hand if you finish before the end of 5 minutes.

Students complete as many problems as possible within 5 minutes. If they raise their hand before the timer expires, I walk by and pick up their paper. At the end of 5 minutes, I redistribute the papers for students who finished within the allotted time so that they can help me check the answers. No student gets their own paper back.

I call on different students to call out the answers and I make sure to review the fractional percent conversions (which were reviewed in the previous lesson), such as questions 2, 4, and 6. 

Class Notes

15 minutes

I determined that students needed more practice with percent discount and tips based on past exit tickets and other formative assessments. I am also taking this opportunity to review some vocabulary words students had not yet been exposed to. Each student will need a copy of the class notes (their pencil) and a white board/marker.

For example, scale factor is a concept students have learned in the map scale lesson. The scale factor is the ratio that relates the original to the model, but students were not introduced to this word when they first learned about scale. I have found this year that my students perform best when introduced to topics incrementally. Calculating actual measurements or scales was a complex process and I wanted to student to practice the skill before learning the word. Today I introduce the word and students will solve problems in the classwork and homework on scale. Formative (as well as summative) assessments in the past have also shown that many students need more practice in this skill to work toward mastery.

Another vocabulary word I introduce to students is “markup” (and I also mention markdowns, which students are responsible for writing themselves). I explain to students that markups/mark downs are related to percent increase/decrease, but used in a more specific context, that of shopping and sales.

Finally, we review a real life example of a problem that includes discount. I want to give bar models another shot, so I use the learnzillion video (link) on bar models and discounts. Students are asked to pick up their white boards after I pause the video at 1:02 minutes. They must complete the work, drawing the bar model, on their white board. Many of my students have not wanted to try the bar model strategies, simply stating their reasons as, “I don’t get it”. I hope to use white boards and a single game of E-race to motivate them to try.

When I ask students to show me their bar models, I ask them to lift their whiteboards. I praise those who drew an accurate picture and ask them to help others who did not fix their drawing. Then, I play the video once more and students add any information they’ve missed. Once the video ends, I answer any students questions and we play a quick game of E-race.


20 minutes


Students put away their notes, white boards and markers are collected by two student helpers as Task assignments are distributed by another student. A timer is set for 10 minutes and students may work with partners during this time. Students must show bar models to solve their problems for this task. As I walk around, I am making sure the shape of these models is accurate for tax/tip and discount. I am also pushing students to calculate the percents by combining where appropriate or by calculating the remaining percent in discount problems. Here are two examples:




I am awarding booths within the first 5 minutes to students showing good progress on the Task and meeting the expectation by drawing Bar Models.

Once the 10 minute timer expires, all students will be asked to return to their seats to finish the Task over the next ten minutes. Those who finish early will be asked to copy their work on the board for questions #1 and #2. I am definitely looking for a student to show their work using the strategy explained in the videos above.


10 minutes

Students who were asked to copy their work on the board will need to explain how they solved. The student selected to show the strategies included in the videos in the previous section will need to be students who are skilled at communication and understanding how the structure of the bar model relates to the real world situation in the problem and how this structure can be used to ask whatever question is being asked (MP7). Students will be allowed to ask questions from their presenters, thus sharpening MP3. Given time constraints, we will most likely only have time to review questions #1 and #2 in this amount of depth and all other answers will be read out loud by students.

Homework will be distributed and the end and students will be dismissed.