From the given sentence, extract the phrase (often noun or verb) that carries the given relationship. The generated phrase should be present in the sentence.

Given Relationship: 'be sign by', Sentence: 'President Bush signed the No Child Left Behind Act in January 2002 , helping change the culture of America 's schools by closing the achievement gap among groups of students , offering more flexibility to states , giving parents more options and teaching students based on what works .'
signed