Didn't understand joke about No Child Left Behind

No Child Left Behind (NCLB) was a US Act of Congress which mandated that all schools which receive federal financial assistance (for the education of children from low-income families) had to administer an annual standardized test to all students.

According to NCLB, each year, fifth graders must do better in the standardized test than the previous year’s fifth graders. Schools that fail to achieve this for two or more consecutive years were required to take certain measures in order to “improve the school”.

As you can see, NCLB was an act centered around standardized testing. Students’—and by extension their schools’—performance was measured and scrutinized by the test scores.

A common criticism of standardized testing is that it leads teachers to focus on test performance, instead of aiming to help students achieve in-depth understanding of the overall curriculum.

Chomsky talks about how he wasn’t able to successfully carry out experiments in the chemistry lab, and yet scored an A by filling out a paper with the results of the experiments, which were quite obvious. He mentions that the this test-centered approach to education had been going on for about 10 years with “no reported progress”, since, he believes, “serious education” is different and does not focus on standardized test scores.

When Chomsky mentions that this failing approach to education has a name, “No Child Left Behind”, the audience laughs and cheers in order to express their agreement with his ridicule and criticism of this act. The reason they laugh is that he refers to his chemistry lab experience as “No Child Left Behind”, even though it predates the passing of the unpopular act by several years.

If someone fails a class, then they can be said to have been "left behind": all the other students are moving on to the next class, but the failed student remains to take the class again (this, along with some related meanings, such as some students not learning as much of the material as others, is what the name of the law is referring to). If a teacher is willing to give an A to someone who hasn't come to any classes, then that suggests that their standards are so low that they wouldn't fail anyone no matter how little the student does.

Chomsky is critiquing No Child Left Behind, a U.S. law requiring each state to set standards for education. Chomsky argues that memorizing to pass these standards facts bores children.

He himself avoided this by not attending boring chemistry classes (long before the law was passed). He calls this boring chemistry class an early example of No Child Left Behind and what he did to avoid it. The audience laughs.

It’s not really a joke.

The modern reference is used as an excuse for his getting a good grade while not participating in the class. In this case he was not left behind despite his not getting on board.