A Percent Equation

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SWBAT solve percent problems using an equation

Big Idea

Solve 3 types of percent problems using 1 equation!


10 minutes

I'll begin with the essential question:  How can you solve percent problems using an equation?  The purpose is to put into students' minds exactly what we are doing today and how we are doing it.

I'll present the percent equation which is an example of modeling with mathematics (MP4). Specific variables are given for each part of the equation, but I will let students know this is not important.  What is important is the following:  part = percent times whole.

Since this is a direct instruction lesson, I will present students with steps to solve.  The steps are to identify the two known values and substitute them into the equation.  Step 2 tells students to solve the equation.  These are both skills students already have experience with.  Now they need to apply these skills to identify whether they are given the part, the whole, or the percent.

Then I will model each example and have students copy my work.  In each example it is helpful to diagram the problems.  See this image for how this looks.

Each example has a check for understanding problem.  Students should solve these problems in the manner of the examples.  It is okay to remind students of each step as they work.

Guided Problem Solving

15 minutes

This section begins with a quick discussion of the two steps to solve each problem.  I include this as a reminder to students that they can refer to their notes.  The two steps are on the previous page.  There are seven problems on the page but if time is short, having students do the odd or even problems and then gp7 should be sufficient.  

Independent Problem Solving

20 minutes

Students will now work independently on this set of problems.  The first seven are virtually identical to the seven problems from the previous section.  Problem 8 ties in a bit of social studies/history though it is really just another use of the percent equation.

Problem 9 does not really seem to follow the core idea of the lesson but I think it belongs nonetheless.  Not only does it give students a chance to exercise their reasoning (MP3) but it allows them to make sense of their answers when solving percent problems.  

Exit Ticket

5 minutes

Before beginning the exit ticket, we will review the two steps to using the percent equation.  Students then have 5 problems to solve.  The last problem, however, has two parts.  This is there a 6 point exit ticket.  Five out of six points will be the measure of success.  That being said, if a student is able to earn four points, they will only need a bit of help to perhaps master this objective.

Also, I will insist that students diagram the problems as opposed to simply selecting the correct answer choice.