The usual path to mastering a target language is to start learning it as soon as possible. There is no doubt that infants learn any language from their parents this way, and can even learn more that one language at a time if they are raised bilingually.
However, in most English-speaking countries the vast majority of children are not in such a situation. Their opportunity to begin learning a second-language will not come until primary/elementary school, when the time allowance will not be generous and the motivation will be mild.
Their teachers model satisfaction with monolingualism and specialist language teachers are in "chronic" undersupply. (Nuffield, 2000), resulting in frequent disruptions and changes in target languages approached.
So what can we offer such children in order that they have opportunity to fulfill their multilingual potential?
Numerous studies since the 1920s have consistently confirmed that learning Esperanto, a language designed to be simple to learn and multicultural in nature, increases a learner’s motivation through a sense of early achievement, leading to a subsequent improvement when learning additional languages. Such a ‘propaedeutic effect’ (facilitating further study) is well known in educational psychology and is regularly exploited
in a range of disciplines from music to mathematics.
The usual experimental model involves two parallel, matched groups of children studying for typically two or three years. One group learns a foreign language – say, French or German – for the whole period; the other studies Esperanto for one year (or longer in some cases), followed by the foreign language for the remaining time. At the end of the experimental period, both groups are given a standardised test in the foreign language. Consistently, the group who studied Esperanto before the foreign language performs
markedly better than the control group.
For example, a study in Germany in the 1970s concentrated on the learning effect that Esperanto had on German children learning English. The study found a gain of 30% in standardised tests when compared with the progress of children who had not previously studied Esperanto; in terms of a five-year course, this is equivalent to a gain of a year and a half.
A similar experiment in Rome, Italy, in 1998-1999 measured the development of language awareness in the mother-tongue of children who had learned Esperanto for one year compared with children who had not. The children were 12-years old at the beginning of the school year. Testing was carried out using a standardised test for measuring language awareness in Italian. Results showed a remarkable improvement in the language ability of children who had learned Esperanto.