Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Las Conicas
In Spanish. Learn how to distinguish and draw each of the conic sections with these activities.
Wolfram Research
Wolfram Math World: The Ellipse
This site explain ellipse how they are formed with the foci, and gives a nice moving demonstration of drawing an ellipse. Read further down the page to equations of ellipses in different systems, including polar. The last half of the...