Percent Change - By What Percent Did the Value Change?

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Students will be able to calculate percent of change.

Big Idea

By what percent did the value change? Can you relate percent change to what we already know how to do? This lesson provides multiple methods of solving.


10 minutes

OpenerAs students enter the room, they will immediately pick up and begin working on the opener – Instructional Strategy - Process for openers.  This method of working and going over the opener lends itself to allow students to construct viable arguments and critique the reasoning of others, which is mathematical practice 3

Learning Target:  After completion of the opener, I will address the day’s learning targets to the students.  For today’s lesson, the intended target is, “I can calculate percent change.” Students will jot the learning target down in their agendas (our version of a student planner, there is a place to write the learning target for every day). 

Thoughts from Me! This concept lends itself to the use of mathematical practices 2 and 4, as most problems can be modeled using real world examples, and given those examples students have to reason both quantitatively and abstractly.  Additionally, students are working with a decimal point - which can change the value of a number drastically if placed incorrectly, so it is important that students pay close attention to precision when working (mathematical practice 6). 

Summary + Homework

5 minutes

Instructional Strategy - Table DiscussionTo summarize this lesson, I am going to ask that students have a table discussion considering the problem “A shirt costs $20, and after tax it costs $21.  What is the percent of tax?  Could this problem be solved using the percent change method?  The reason I am having students talk about this problem is to draw connections to previous lessons, as well as shed light on another method of solving the problem.  Students have already learned percent change, just in a different context, and the way that we learned to do it in earlier lessons does apply and is a valid way of solving the problems in this lesson. 

Percent Change Homework: As students are having their table discussion, I will pass out the night’s assignment.  This assignment allows students the opportunity to practice percent of change problems.  Students will be asked to look over the assignment and identify any glaring questions before they leave class – I want all students to experience success!