I'm not familiar with the nuances for the YYZ-YVR pass options, but for my travel, I found a general population pass to be better than the student one. It was available in fewer credits, had a longer validity, no peak surcharge and was essentially the same price. I also had the flexibility to share my credits with another person if I wanted to, plus a more generous booking class (don't quote me on the details, it's been a while since I purchased, and it was a different route).

While the pass is nice since you're locking into a fixed price, there's some pressure to use all the credits, especially if your child might be on the fence about going home for a reading week (they might be a fan now, maybe less of a fan when burried in assignment and tests). On a route like YYZ-YVR, ULCCs might be another option too if they don't need to transport too much stuff for shorter trips.
​​​​​​
​​​​​​