Being a student in Toronto can really, really suck. If you're not living near your campus you've got the price of a Metropass, plus food and then ... if you want to have a social life or do anything on your days off, you've got another issue on your hands. Luckily, there's quite a few attractions in the 6ix that offer some sort of discount (or even better, free admission) for students.
Every Tuesday the Royal Ontario Museum offers post-secondary students free admission to all general exhibits. While this won't include special galleries like the Out of the Depths: The Blue Whale Story, it still includes a multitude of artifacts to explore.
Beta Shoe Museum
Thursday nights between 5-8 p.m. are always pay-what-you-can at the Beta Shoe Museum and student admission any other time is only $8. With over 13,000 artifacts spanning 4,500 years, shoe lovers will surely find pure joy here.
The Art Gallery of Ontario offers free admission to everybody between 6-9 p.m. every Wednesday that it's open. Like most other attractions, this only includes general galleries, but these will take at least a few hours to make your way through.
The Gardner Museum
On Tuesdays the Gardiner offers free admission to post-secondary and on Fridays between 4-9 p.m., admission is half price. The museum is currently featuring an exhibit of contemporary Inuit ceramics and details the traditions of creating these pieces.
You got me; this attraction doesn't actually charge people for admission but it's still worth mentioning. It's a great place to explore during the winter when it's freezing outside and if the whole "free" concept doesn't interest you, you might be interested in taking a peek at the baby turtles that call Allan Gardens home.