There are two great ways to see the Royal Ontario Museum in Toronto for cheap (or free!) each week:
On Wednesdays, general admission to the museum is free from 4:30 until the museum closes at 5:30.
On Fridays, admission is half-price from 4:30 until the museum closes at 9:30.
Tickets for adults are $20 and for students, $17, so the savings available on Wednesday and Friday afternoons are pretty significant.