Math problem

There were 2 young boys, one was Jewish and the other Christian. 
The Christian boy was unbelievable at math, but the Jewish one had a very hard time with it. 
The Jewish boy went to a day school while the non-Jew attended a very good Christian private school in the area. 
The Jewish mother knew that the Christian school had a great math program and she really wanted her son to improve his skills so she decided to send him to the Christian school. 
2 weeks passed and the young Jewish boy was extraordinary at math. Any porblem his mother gave him he could do it in the blink of an eye. 
She said to him, "Listen, I don't understand you didn't know any math when you were at the Jewish school and now that you're at the new Christian school you're amazing, what changed?" 
The boy responded, "Ima, once I saw that guy nailed to the addition sign I really sucked it up!!!"