Tracking Stocks and the Coordinate Plane

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SWBAT: • Define and find absolute value • Compare absolute values • Plot points on the coordinate plane • Identify points on the coordinate plane

Big Idea

Which stock price had the largest change? How do you know? How do you represent a point on the coordinate plane? Students continue tracking their investments.

Do Now

10 minutes

See my Do Now in my Strategy folder that explains my beginning of class routines.

Often, I create do nows that have problems that connect to the task that students will be working on that day.  I want students to apply what they learned in the previous lesson (Absolute Value and Stocks) to the question of largest change and smallest change in stock price.  I want students to recognize that Google had the largest change, because the absolute value of its change is the largest compared to the other changes. 

I ask for a volunteer to share out his/her thinking and answer for each question.  If a student correctly answers the question, I declare that I think that Apple’s stock price had the largest change, because its stock price increased $14.79.  I want students to be able to articulate that we can think about largest change as distance.  The stock price with the largest change is the one whose August 9th stock price is furthest from its May 21st price.   If we find the absolute values of the change in price, we find the largest and smallest change.

Tracking Investments Practice

10 minutes


  • I give each student a calculator to calculate change in stock price.  I want students to focus their energy in analyzing the changes in stock prices.  Furthermore, adding and subtracting rational numbers is a 7th grade standard.

I present my investment information and explain that students will be going through the same process with their investments today.  We calculate the change in stock price by subtracting the Day 2 Closing Price by the Day 1 Closing Price.  We check our calculations by looking at the change.  It makes sense that Amazon’s change in stock price was positive, since the closing stock price increased from Day 1 to Day 2.  On the other hand, it makes sense that Game Stop’s change in stock price is negative, since the closing stock price decreased from Day 1 to Day 2.

Next we find the absolute value of each change in stock price.  Then I ask students to identify which stock price had the largest stock price and smallest.  Students participate in a Think Write Pair ShareI call on a couple students to share their ideas and ask other students to share if they agree or disagree and why.  Students are engaging in MP3: Construct viable arguments and critique the reasoning of others.

I show students the rubric on page 9 of the “Tracking your Investments” packet.  I have volunteers read the descriptors for each number, and then I ask students to rate their own work on this practice page.

Tracking Your Investments

15 minutes


  • Students began this project with the lesson Absolute Value and Stocks.
  • Students must have Part 1 completed before they can complete Part 2a.
  • I create a spreadsheet with the closing stock prices of each company.  I post a number of these around the room for students to use.

I have a volunteer read over the to-do list for this part of the lesson.  I explain that if part 2a is not completed during class it will be additional homework.  I call students by rows to find a Closing Price Spreadsheet around the room.  They copy the closing price of the companies they have invested in on their packet. 

Students work independently with their calculators.  Students are engaging with MP2: Reason abstractly and quantitatively.  As I walk around, I monitor student progress.  A common mistake is that students find the change in closing price by subtracting day 1 – day 2.  If students do this, I refer them back the practice page to review.  I also ask them if the closing price increased or decreased from day 1 to day 2.  If the closing price increased, does it make sense that the change in price is negative? 

If students successfully complete part 2a, I remind them to read over the rubric and make revisions.  Once they are finished they can work on the Unit 3 Challenge about percent change.  I allow students to use calculators.  This challenge can carry over the next few lessons.

Coordinate Plane Notes

5 minutes

I ask students to use the picture to figure out the missing words in the notes.  We read through the notes together and review how to identify and graph an ordered pair.  I ask students how they remember which point to go to first?  Some students may share that x comes before y in the alphabet, so they remember that the first coordinate is the x value and the second coordinate is the y value.  Other students may have other ways to remember how to plot ordered pairs.

Using the top picture, I ask students to list ordered pairs that fall in Quadrant 1.  I create a list labeled, “Quadrant I” on the board and write the ordered pairs underneath.  I do this with each quadrant, and then I ask students, “What patterns do you notice?”  Students participate in a Think Pair Share.  I want students to recognize that if both of the coordinates are positive the ordered pair will be in Quadrant I and so on.  I push students to see a pattern with the ordered pairs of each quadrant.  Some students may notice that if an ordered pair contains a 0 it falls on an axis.  Students are engaging in MP8: Look for and express regularity in repeated reasoning.

Coordinate Plane Practice

10 minutes

Students work on the Coordinate Plane Practice independently.  Common mistakes include switching the x and y coordinate and not understanding what to do if a coordinate includes a zero.  If I encounter these mistakes, I refer students back to our notes and have them look at our examples.

I Post A Key so that students can check their work once I take a look at it.  If students successfully complete the practice they can move onto the Coordinate Plane Puzzle.

Closure and Ticket to Go

10 minutes

 For Closure I ask, “If the first coordinate in an ordered pair is negative and the second coordinate is positive, which quadrant is it in?  How do you know?”  I call on a few students to share out their ideas with the group.

 Then I ask students, “What does it mean if the change in a closing stock price was -$4?  What about +$4?  I want students to be able to articulate that the change in a stock price is negative if it decreased over time and positive if it increased over time.

I pass out the Ticket to Go for students to complete independently.  At the end of class I pass out the HW Tracking Stocks and the Coordinate Plane.