Parents are concerned that children who have trouble in school will 'fall through the cracks' in the school system. [=will not be given the help they need; will graduate without anyone noticing that they are unable to do the work]
The program is meant to help workers who may have 'slipped through the cracks' [=who may have not been included in other programs] because of their age.
You ought to 'get cracking' [='get going; get moving'] on that assignment. [=you should start working on that assignment right away]
(..) Your faithful sister, Sansa. - They forced me to do it. - Did they? With a knife at your throat? Did they put you in a rack and stretched you till your bones started to crack? You should have known what it was like. I was a child. So was I. I would have let them kill me before I betrayed my family. (..)2017 TvShow: Game of Thrones Title: Beyond the Wall Season: 7 Episode 6
(..) Now he's dead. Killed by the Lannisters. With your help. What? That's your pretty handwriting. Septa Mordane used to crack my knuckles cause I couldn't write as well as you. Robb, I write to you today with heavy heart. Our good King Robert is dead. - Killed from wounds he took in a bull... (..)2017 TvShow: Game of Thrones Title: Beyond the Wall Season: 7 Episode 6