1) Schools could ensure that motivated students participated.
2) Teachers could ensure that children gain more from working together.
Sentence 1 is about a hypothetical scenario in the future. This is why we have "could ensure" and "participated", but I saw sentence 2. It has "could ensure" but with the verb "gain".
Why is this? What is the difference in the meaning? If it not a hypothetical scenario in the future , why did the writer bring "could ensure"?