Lesson Plan Ideas: Calculating Slope in Algebra II

Graphing and Slope 45 minutes

Linear Relations and Functions Lesson #3: Slope

Context

This is the third lesson of the unit. Students should already have basic knowledge concering the coordinate plane and how to graph points. Students need to know the formula for slope but understand the concept of slope as well. Students will be working with slope throughout the rest of the chapter so it is vital they know the formula very well. Understanding the concept is extremely important too, especially when we get into scatter plots where they will have to evaluate the slope of graphs.

Objectives

Students should understand the concept of slope and be able to calculate the slope of a line given two points on a graph. Students should be able to calculate the slope of a line that is parallel and a line that is perpendicular to a line with a given slope.

Resources, Media and Technology

Graph Board

-Ruler or Meter Stick

Procedures

Before class begins, I will write notes on today's lesson on the board giving me a brief outline of what I want to cover and when I want to cover it. I will instruct the students to copy the notes while the morning announcements are being made. Next I will proceed with the lesson on slope. I will start the lesson by giving a formal definition of slope. I will use a ruler and real-life examples(ex: WKU's hill) to help demonstrate what slope is. I will then go into the formula for slope. I will write the formula on the board for the student's to copy and then I will explain what each variable in the formula is. Then I will show how it is determined what y1, x1, y2, x2 are. To help them memorize the formula, I will also mention to them the "rise over run" strategy.

I will actually show them how slope can be found on a graph by just using this strategy. I will show them how to make the slope go in one direction and then show them that by changing the sign of the numerator and denominator, I can make the slope go in the opposite direction. Then I will plot a couple of points and do an example. I will probably do one or two more examples on the board before I start calling on students to help guide me through the problem to make sure they understand the steps that are involved in computing slope. Throughout the examples, I will explain to the students how to determine if the slope is positive or negative just by looking at the graphs. I will explain the differences in positive and negative slopes and what they will look like on a graph. Next, I will demonstrate "zero slope" and "undefined slope" using the ruler and hill example.

I will write the slope values on the board to show the students what an undefined slope value will look like(3/0). Finally, I will cover slopes of parallel and perpendicular lines. I will once again use the ruler to explain why parallel lines have the same slope. I will do an example on the board where I find the slope of a line parallel to another line. Then, I will explain that perpendicular lines have opposite inverse slopes, and I will do a couple of examples on the board for them to see. I will finish the lecture off by having the students work out a couple of slope problems dealing with parallel and perpendicular lines. I will walk around the class to answer any questions and also to make sure most of the class understands the necessary steps in order to find the slopes of lines. The students will be given their assignment and handed their quizzes back to finish off the class.