When we've got a seriously underachieving youngster, it's awfully tempting to resort to taking away all sorts of things in a desperate attempt to motivate them to do their schoolwork. Sadly, this often backfires, leading the child to become even more resistant about learning.
Most of us wouldn't feel that motivated if our spouse said, "Ok, that's it! No more golf [or whatever else we might love to do] until I start getting some better reports from your boss!"
While it's entirely reasonable to set some limits on TV, video games, and other entertainment activities when kids are doing poorly in school, taking them out of their favorite sport, Boy Scouts, music lessons, etc. is a bad idea. The research is clear on this:
Kids who are struggling in school need at least one natural high…so that they aren't so tempted by various artificial ones.