Translation:The students need more practice.
'The students need more exercise' is a perfectly logical translation (although obviously not intended), and should be accepted, because 'oefening' means both 'exercise' and 'practice' (UK Eng).
Can one also say "De studenten hebben meer oefeningen nodig" (for "the students need more exercises")?
I just got this wrong, the tip said ""The students need more exercise" implies physical exercise, which is not what the Dutch sentence means." Is there anything other than context to imply that we the dutch sentence refers to practice of a particular subject/skill instead of physical exercise?
To practice = oefenen, so a verb (infinitive). "The students need to practice more" would be "De studenten moeten meer oefenen". Hope this helps.