Ok, so the use case for your method `students_by_high_score` is that we need to filter down students to ones that are associated with a particular team. Instead of doing this in the database, we should do it in Ruby. Ruby has a method `Enumerable#select` that can be used on arrays. It can be passed a block which is executed once for each item in the array. If the block returns true, the item stays, and if the block returns false, it does not.

http://ruby-doc.org/core-2.0.0/Enumerable.html#method-i-select

E.g.
```ruby
[1, 2, 3, 4].select { |n| n % 2 == 0 } # => [2, 4]
```
In this particular case, we want to loop through `students` and filter down the array to only students whose id is in `team.student_ids`.

Does that help?