#### Activity Overview

This activity allows students to explore situations in which points with a constant difference between coordinates are graphed. With TI-Navigator?s display, students can determine that an oblique line is formed from such points. This oblique line always has intercepts equal to the constant difference and the opposite of the constant difference. The Learning Check enables the teacher to get immediate feedback from the students, thus giving opportunities to correct any errors in understanding.

#### Before the Activity

Before the Activity create a Learning Check that has the questions: If a line has points for which the difference between the x-coordinate and the y-coordinate is 9, what kind of line is it? Horizontal Oblique Vertical If a line has points for which the difference between the x-coordinate and the y-coordinate is 9, its graph has an x-intercept of ____ and a y-intercept of ____. If a line has points for which the difference between the x-coordinate and the y-coordinate is 9, its graph passes through which quadrant(s)? Quadrant 1 Quadrant 2 Quadrant 3 Quadrant 4 Start TI-Navigator and begin the class.

#### During the Activity

See the attachment

#### After the Activity

Send a Learning Check file to the class to check for their understanding. The first question is a multiple choice one. If a line has points for which the difference between the x-coordinate and the y-coordinate is 9, what kind of line is it? Horizontal Oblique Vertical The second question is a fill-in-the-blank type. If a line has points for which the difference between the x-coordinate and the y-coordinate is 9, its graph has an x-intercept of ____ and a y-intercept of ____. The third question is a multiple choice one for which there is more than one correct answer. If a line has points for which the difference between the x-coordinate and the y-coordinate is 9, its graph passes through which quadrant(s)? Quadrant 1 Quadrant 2 Quadrant 3 Quadrant 4 Collect the answer files from the classroom. Display the slide show of student responses and discuss the results.