Instead of moving the student to the next grade, there are plenty of things you can do to make sure these students have a deep understanding of their current grade level content.
They can, of course, take on the Challenge Objectives. These puzzles require perseverance and problem solving but are super fun!
You can look at where the student might have struggled and have them go back to those Objectives using the History button on the student home screen.
You could also have them go deeper into the games using the ideas on this Project Board and accompanying rubric.