You should consider why you need to use distance learning and why you need technology for a particular subject. Can you get the same educational materials from a textbook? Which technologies do you plan on using? You can use the internet to gather material from the internet or you can join a "tele-classroom" and watch lectures, live or pre-recorded, on the internet, but do these tools have any advantage over the conventional route? If you experience "technical difficulties" in the middle of the lesson, will you miss a lot or be able to go back and see what you missed? Will you be able to hear the lecture or ask questions if you don't understand what the teacher is saying? These are all things to consider.
Which subjects make the best candidates for distance learning? Usually subjects that traditionally required student interaction, such as English class or foreign languages, don't make very good candidates for distance learning. Too much is lost by not being able to interact directly with other students and teachers, that such a course would not give the student the full experience necessary to make it useful. Instead, physics or mathematics courses are pretty good candidates since most of the studying is done out of the book by the student. A student can always refer to his book if he needs, but the same isn't always true of other classes.
When you've considered these points, you'll be in a good position to make the lesson plan for distance learning. Remember to consider other options before going straight to a technology solution, since it can complicate things quite a bit. Sometimes, the best option IS distance learning, so good luck.
