Activity Overview
In this activity, students create a slope triangle and understand the concepts of slope and the equation of lines. They realize that slope is constant at all points along a fixed line. They also explore the slopes of parallel and perpendicular lines.
Before the Activity
Install the Cabri™: Jr. App on the students' graphing calculators using one of these two methods:
TI-Connect™, a TI Connectivity Cable, and the Unit-to-Unit Link Cable
TI-Navigator™ "send to class" feature
See the attached PDF file for detailed instructions for this activity
Print pages 1 - 7 from the attached PDF file for your class
During the Activity
Distribute the pages to your class.
Follow the Activity procedures:
Draw a horizontal segment and construct a point on the y-axis
With the length of the segment as radius, draw a circle with the point as the center
Enlarge the circle so that the point in the first quadrant is in the upper right corner of the screen
Construct a point on the circle in the first quadrant and draw a line connecting it to the center
Hide the circle and the segment, and construct 2 points, A and C, on the line
Draw a perpendicular from C to the X-axis, and a perpendicular from A to the Y-axis
Label the intersection of the perpendiculars as B
Hide the perpendicular lines, draw segments AB and BC, measure their lengths, and compute the ratio BC/AB
Drag A or C along the line and observe the variation in the value of the ratio
Display the equation of the line and its slope
Rotate the line around the y-intercept and examine the relationship between the slope and the equation
Observe the changes in the equation as the y-intercept is changed
Explore the slopes of parallel and perpendicular lines and determine the products of the slopes of perpendicular lines
After the Activity
Review student results:
As a class, discuss questions that appeared to be more challenging
Re-teach concepts as necessary