We have almost all heard of Phoenix Online and Walden University. These are very popular, and regionally accredited colleges that offer online classes and degree programs. But, you should know that colleges in your local area may have online classes that are less expensive. For example, Walden University charges a tuition of $425 per credit hour for online courses, according to their tuition and fees information page for 2009-2010. When checking tuition for Phoenix Online, the information page quoted a $540 per credit hour fee, in accordance to my zip code. On the contrary, one university in my city would charge less than $200 per credit hour, because I am a resident.
If there are no colleges in your immediate area, check with the Department of Education for accredited colleges in your state.
I promote taking classes in your own state for these reasons:
1. Tuition is usually lower for residents.
2. Continuing education courses will likely be applicable (you wouldn't want to waste your money on courses that are only applicable in a state you will never reside in).
Another option that elementary teachers may want to consider when pursuing online continuing education classes, are the free classes offered by schools like MIT and Yale. Many reputable colleges offer free online courseware. Of course you have to purchase the books, but many can easily be found on Amazon, or similar websites. One thing I stress when opting for open courseware is, you must be self-motivated. The great thing is, there is no time limit. In my experience, you follow the instructed syllabus, and do it at your own pace.
Please note, if you are looking to obtain continuing education for salary advancement, you must contact your own school district for their policy on taking courses online.