Delicious Percents

Personal Reflection:
It's that time of year!  We started 7th grade off this year with a quick and dirty unit on percents.  It's my first time teaching 7th grade in 11 years, and this is a completely different population than I last taught.  The standards have changed, the expectations have drastically increased, and I'm desperately searching for ways to engage the students in real-world mathematics.  So, as I look for real world applications of percents, I found this "draft" post I started ages ago.  Perfect for my lesson this week on percent increase!

Grade Level: 6-8

Course: Math, Pre-algebra

Standards:   7.RP.3

SMP: MP1, MP2, MP3, MP6
Skills:  Solving problems with percents, finding percent increase, analyzing and interpreting mathematics.

How to use this as a mad minute:
Depending on the performance/experience level of your students, you may be able to accomplish a successful analysis of this problem in 1 minute.  If so, I would simply ask, "If a normal package contains 1 bar, and the new package contains 2 bars, is that a 200% increase?  Why or why not?"

How to use this as a warm up:
The only difference in how I would use this as a mad minute, warm up or mini-lesson is in the amount of time it would take for students to successfully analyze, interpret, and debate the reasoning in the ad.  If your students are nearly proficient with this skill, they should be able to tackle this in a 5 minute warm up.

How to use this as a mini-lesson?
As outlined above, students who are not yet proficient may need up to 20 minutes to talk through the fundamentals of percent of change, percent increase, etc.  I know that my students will need about 15 minutes to thoughtfully and successfully approach this problem.  Here is my sample "script outline" that I plan on using this week with my students.

• Mathematicians "wonder mathematically" and analyze the world around them, thinking about mathematical claims they see.  
• Here is one such example.  (Review the claim of the ad.)
• What do we already know about percent change, or percent increase?
• We know that we need to find the amount of change
• We know that we need to find the original amount
• We know that we need to divide to get a decimal.  
• We know that we need to convert our decimal to a percent.  (Alternatively we could find an equivalent fraction with a denominator of 100 in order to find a percent.)
• Knowing how we find percent increase, analyze this advertisement and prepare a short response (rebuttal, if your students can handle the vocabulary) regarding their mathematics.
• (Have students share out.)

How to use this as a full lesson?
I do not think this would warrant a full lesson in most classrooms.

How to use this as an assessment?
I would DEFINITELY incorporate this as a question on an assessment once I'd reviewed these skills with my class.  It's not too sophisticated to "mystify" students in an assessment setting.  Just remember to push your students to think this way and develop such arguments PRIOR to the assessment!  :)


Please feel free to use any of these ideas and modify them to meet your needs.  However, please acknowledge the original source of the items and my own lesson outlines.  ©NatalieRSprigg 2014