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]家长们担心，学校里那些问题学生会被现行的教育体制所忽略。

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.这个计划的目的是要帮助那些因年龄问题而未被其他计划惠及的工人。