Yes, there are part time TEFL courses. You can also do a part-time CELTA course, typically they take about 3 months to complete and involve you attending class two evenings per week and some Saturdays.
There are advantages to part-time and full-time courses. Part-time TEFL courses are less hectic and give you time to absorb the feedback and information that you get, as well as to do extra reading. However, most people find it difficult to juggle work, family and course, and to concentrate for the whole three- to six-month period that the course takes. It can also be difficult to find local part-time courses that are close to home and start at a convenient time. Four-week full-time courses are incredibly intense and you won’t be able to get anything else done during that time, but at least you should be able to put your life on hold and/or move away for that period and so be able to concentrate. They are also good preparation for the pressures of your first teaching job.
If you are not able to quit your job and do a full-time TEFL course then it is probably best to do a part-time course, and/or an Online TEFL Course.
Remember, with an online course you can study at your own pace. You can continue to work full-time whilst studying. You can log-in whenever you want from any device you want. You can take as long, or as little, to complete the course. You can read, re-read and re-read again. There is no pressure from anybody except you to complete the course.
It will depend on your personal circumstances as to what course is best for you.
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