“Intelligence is like the horsepower of a car. A powerful car has the potential to drive at speed. But you can have a powerful car and drive it badly. Thinking is the driving skill with which each individual drives his or her intelligence." (Edward De Bono, 'Mind Power' 1995)
Choosing Esperanto as the first foreign language can improve both the “horsepower” of the brain and the “driving skill” of its owner by both changing the physical structure of the brain, and providing more practice in higher level thinking skills.
The structural brain change (visible on a scan) is the same whichever second language is mastered, but is more marked if the second language acquisition is early and thorough, both of which are much more likely in Esperanto than in other languages which might be introduced in school. This change " enhances a person’s ability to concentrate". (Society for Neuroscience, 2008)
All language learning requires some memorization, involves some understanding and application, and has potential for analysis, evaluation and creativity.
If our time was limitless, we could explore the full potential of any language, and experience a balanced combination of thinking tasks, as the green shape shows, in any language.
However, our time is always limited, so that a larger number of symbols and sounds, and conditions for matching them, basic roots, synonyms, homonyms, homophones, rules that sometimes apply, rules that occasionally apply and exceptions..... take time which could be used for broader and deeper application, analysis, evaluation and creativity.
If the goal is to keep students busy, it doesn't matter either way, but if the goal is to develop high quality thinkers, it does matter how they exercise their brains.