Lingopolo is based on the method which the world's leading language organisation, SIL, uses for their staff to learn languages with one-on-one language helpers. SIL are the leading experts on world linguistics. It is SIL who are the authors of the Ethnologue, the definitive guide to the world's languages.
It is an aural method based on the principle of learning increasingly complex comprehensible input.
It is very closely related to Stephen Krashen's Theory of Language Acquisition.