I'm looking for a synonym for "curious" that is undoubtedly positive. "Curious" itself is fairly neutral--it could be interpreted as a good thing, but it's sometimes seen as a bad thing (i.e., "Curiosity killed the cat."). There are plenty of other synonyms that are wholly negative: "nosy," "snoopy," "prying," etc. Are there any other synonyms for "curious" that make it clear it's a good thing, such as to describe someone who's curious about an academic subject and wants to learn more about it?
I think if used in the context you've described curious will consistently have a positive connotation; I can't conceive of how curiosity about an academic subject could be taken negatively.
Perhaps the word 'interested' is less likely to be construed negatively. "She was interested in biology".
I think that any negative connotation attached to any word that describes inquisitiveness stems from the human desire for privacy; there will always be certain subjects that people don't want examined, as such there will always be the potential for any type of inquisitiveness to be spun negatively.