I think the majority of uni/tafes classify mature age students as 25yrs and older.
We've got quite a few mature age students and I have to say they do tend to know a lot more and be able to concentrate on study more than us younger kids. Im going to be 23 when I graduate, even though i went straight from yr 12 to school (wasted 3 yrs on primary education) and I feel old but not compared to others lol.
I admire mature age students, esp those over 30yrs, coz most of them are like single parents, or single income families, who are going back to study to further their careers, and make a difference for their families. And sacrifice heaps! That takes a lot of courage! So well done.
Though we did have one annoying lady who one time came in late and sat next to me and my friend and then in the middle of the lecture, she yells out are you from USA? And the lecturer looks up in suprise going oh yeah i do. And then the lady goes oh well I want to thank you for coming out here and teaching us...blah blah and me and my friend were like OMFG!! Then she moved down the front a bit, and then moved again even further adn we were all like whats she on?! I dont think ive seen her since...hmm