students from class UK were divided into two groups, positive contribution group and negative contribution group.According to the study of a famous "people's scientist" of that time(1600s), these negative contribution people don't do any positive work for the sociaty but consumes a lot of resources.

Some people in the negative contribution group were sent to the New England to form a slow class. Later on the students in this slow class were found to perform comparable, or even better than those students who studied in the UK class.