Many companies advertise low participant-to-instructor ratios as a marketing ploy, however other motivations come into play here. The reasoning behind the participant-to-instructor ratio motivations is not just about small class sizes and individual attention, but also the legal status of the TEFL / TESOL training provider and its trainer. If the business is unregistered, then the business obviously cannot provide a work permit for its trainer, so they tend to operate under the radar not to alert immigration.  There are basically two types of companies to look out for and easy to spot if you know what you are looking for. The first type is; TEFL providers that cap their classes at 9 or below from a static training location.  The reason for this is that Thai law states that if you are training/teaching more than 9 people you must register your business as a “tutor shop”, obtain a work permit to work legally, and start paying taxes on your income.  The second type is; TEFL providers that take as many people as they possibly can get and continually rotate their training locations each month to different hotels/resorts or rented training locations.  These types of companies are very easy to spot as they will not have a physical address on their website anywhere as they tend to get raided by immigration and their students held for questioning. The participant-to-Instructor ratio is important to receive individual attention and make sure you get all the guidance and instruction you possibly need.  At Entrust TEFL, our participant-to-instructor ratio is 15-to-1, and have three full-time trainers on staff that help break up the classes into smaller groups when doing peer-2-peer teaching, curriculum design, and other group activities.