Translation:The students study to gain knowledge.
I'm having an issue with "para". Now that I have been tutoring the romance languages for four years I am positive that "para" means "in order". That's why it goes in front of infinitives. "The students study IN ORDER to gain knowledge". I know you don't need it there because in English we don't have to say "in order", but it still is the same whether it's used or not and it keeps saying I am wrong when I use it. People should know what it translates to say they know where to put it in the sentence. It should be correct to say "the students study in order to gain knowledge". Otherwise those who are studying won't know that "para" has more than just a few definitions.
I concur strongly with your point and have found this particular meaning and an example of it given in a Portuguese Learner's Dictionary (Oscar Fernández, revised and updated by Jura D Oliveira). 'Vou agora para não chegar tarde'...'I'm leaving now in order not to arrive late'. But maybe another revision is needed as the language has moved on??