Earlier quoted context omitted.
It would work short term, but I would worry that it makes a a price to be paid which will impair joy in learning the subject in the long term. Its much better to make kids interested in learning than to reward reaching goals or punish failing to reach them.
On the other hand, the kids might do lot of exercises to keep playing, then they get better at something, then they realize that it is much more enjoyable to be good at something than not... Long term, it could still be a win. Obviously not the same, but in the first years of university, I hated math because it suddenly got hard (never before university did I have to learn math or physics just to barely pass). Then,…
This is still useful after having left academia, I often look at something and the right "tool" pops up from the toolbox. It helos to understand the world around us and realize how much bullshit we are fed through doctored graphs or tables.