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]
(..) "Against Asia's endless hordes, against all odds, we can do it. We can hold the Hot Gates. We can win." Dawn. Whips crack. Barbarians howl. Those behind cry, "Forward!" Those in front cry, "Back!" Our eyes bear witness to the grotesque spectacle... ...coughed forth from the darkest (..)2006 300
(..) Be unfortunate if anything were to happen to him. Or to his beautiful mother. No! Our Greek comrades are begging for a crack at the Persians, sire. Good. I've got something I think they can handle. Tell Daxos that I want him... ...and of his best eager, sober (..)2006 300