How do I start teaching in colleges/universities, so that I can assure myself work once I retire from my teaching job?
I think the best way to begin is to apply as an adjunct, perhaps starting with summers. You can teach classes every now and then in the evenings or online. You also might want to consider a community college, so that you will have some college experience once you retire, but advanced degrees are usually not required at the community college.
The above posters make excellent points. I might add, that colleges will be looking more and more toward adjunct or per course professors. With the economy issues carrying the weight of full-time and tenured professors is going to be more of a finincial burden than many colleges want to carry. That being said, there will be more applicants for these part time teaching jobs. Keeping this in mind, it would be a good idea to network, and build a series of contacts that can put in a good word for you.
Be sure to check to see if the the college or university takes part in the same retirement system as your public high school. I found this to be the case in Georgia. I teach high school during the days, and I supplemented my income by teaching college courses at night. Colleges are usually looking for people to teach their freshmen composition courses, and they pay very little for the amount of effort that they take. Anyway I found to my surprise that I could not retire from public schools and teach full time at the college level because they were part of the same retirement system. I could teach, though, at 49 percent of my current salary. Just something to check into.
In my area, colleges are looking for adjunct professors. I had no trouble getting hired to teach a course a semester. I was asked to teach two, but that would have been too much. Even one course, twice a week, was more than I was willing to do for very long. Good luck with this endeavor. It is not an easy one.
As you currently teach in the public school system, and at the elementary level, check to see if there are education classes you can teach on a part-time/adjunct basis so that you can build a reputation as a college instructor with the staff and administration of a college, and a history of success with college students. This will increase your chances.
If you wish to teach in another subject area in which you have a Master's Degree, keep in mind that full time positions are currently being cut across the board as states are facing massive budget shortfalls. This is adding to the number of part-time instructors in the labor pool, and making it more difficult to break in to teaching at that level.
I moved from teaching high school full time to teaching at a community college part time, so I hope I can give you some relevant advice.
First of all, you need to find out what qualifications are needed. Four year colleges will typically want you to have a doctorate while you might get in at a community college with only a masters.
Second, you should try to get on as a part-time or adjunct instructor. Your best bet for this is to see if the colleges run any night classes. Those will probably be less popular with the full time or more senior instructors.