http://www.math.missouri.edu/~bartonae/pplane.html

Online software to make phase portraits from any browser.

Useful on the 9.4 problems. Also useful for final exam study, chapter 9, sample final exam.

Google search string:  "online free pplane"

The best links are: (1)Missouri, link above, and (2) Rice University. The program pplane
was written by J. Polking, at Rice.