"The exams are just challenging enough to reduce the graduation rate," Professor Warren added, "but not challenging enough to have measurable consequences for how much students learn or for how prepared they are for life after high school".
But it's progressively challenging enough to feel like more than just a cash-in.
We all need goals to motivate us and these have to be challenging enough to excite us, but also achievable.
"You want anything else?" The first lady demurred, saying it would be challenging enough to fit the pumpkins on the bus.
For adults, it's challenging enough to sit through 20 or 30 minutes of speeches, but for 12- and 13-year-old kids, it's especially difficult".
Back in 1984, he gravitated toward gunpowder because other media were not "destructive enough, subversive enough or challenging enough to myself".
Even with such help, there are still several European countries in which match-fixing is not a criminal offence, which complicates an investigation process that is challenging enough to start with.
As if it were not challenging enough to re-create old dances, make new ones, and present them on tour in cities around the world during the next year or so, Cunningham has also just published a book.
By "this stuff," she means terrain that is challenging enough to fit under the standard definition of extreme skiing, first codified by the American steep-skiing pioneer Chris Landry: "If you fall, you die".
Had it done so — had it felt a little less optimized for escapist viewers — it might also be a bit harder to watch, challenging enough to risk discomfort, even alienation.
