I realize that I did not include gravitational pull and other factors but I created a simplified version so students could see the use of ellipses in real life.
I had them begin with the information on The Universe Today for both the closest and farthest distances from the sun. The farthest distance was designated as the a value while the closest distance was designated as the b value for the basic equation.
After creating the basic equation, they calculated the value of c using c^2 = a^2 - b^2 because they needed it to figure out eccentricity or e = c/a. After getting this done for each planet, they used Desmos to graph the orbits.