Instructions:
1) In the applet below, note the slope displayed in blue.
2) Drag either one (or both) of the purple points below so that the slope of the purple line matches the slope displayed.
3) Click the "Show Hint" checkbox if you would like a hint.
4) Once you determine any one (out of infinitely many) correct possible positions for the line, the applet will indicate you've done it correctly.
5) Click on the "Generate New Slope" button to create a new slope.
6) Repeat steps (1) - (5).
7) Repeat steps (1) - (6) as many times as you need in order to master this concept!

Key reflection questions:
1) What causes a line to have POSITIVE slope? Explain as best as you can.
2) What causes a line to have NEGATIVE slope? Explain as best as you can.
3) What causes a line to have ZERO slope? Explain as best as you can.
Even though you didn't see an example like this in this applet, what kind of line would have a slope that is undefined (i.e. nonexistent?)