The "Recommended lesson" at the top of the online lessons page is now definitely recommended:
This is the lesson of All Thai content on Lingopolo, both words and phrases. The really great thing about this lesson is that it automatically takes you through from the simplest most common word (which is the "polite particle for male speakers"), all the way through to the most complex Lingopolo phrase (which is currently "In Thailand every house has a fan because the weather is very hot"). Of course, it automatically takes account of exactly where you currently are in your work on any of the other lessons.
Below is an example of the order in which this recommended quiz will teach you. As soon as Lingopolo has taught you the word for Thai, it will straight away start to teach you phrases which use the word for Thai. It will teach you the phrase Thai language, then the phrase I cannot speak Thai, then the phrase He speaks Thai.
Once these are taught, it will teach you the next most frequently occurring word, the word for What?. With that it will then teach you What do you like? and What language does he speak?
Basically this lesson will teach you everything on Lingopolo in automatically the optimal order.
Happy Lingopolo Thai study!