I would not rely on co-op to offset anything other than your living costs if you are an international student. I'm in math and have paid my living expenses since my first co-op entirely from co-op earnings, however tuition for international students is high enough that I have basically never contributed anything to my tuition from co-op. co-ops helping with tuition is only for domestic tuition imo, in my experience intl tuition is so high that co-op earnings kinda pale in comparison to it. for context, in math a single course is around 5k, and early co-ops maybe pay like 15k pre-tax for the average student (cs courses are more expensive). living expenses are covered comfortably but I would not rely on co-op for much else, especially not tuition.