有句英文不理解在文中啥意思

问题描述:

有句英文不理解在文中啥意思
根据上下文的意思情帮忙解释一下“Here is one more;and one and two make three.So here are three chickens”这句话在文中的含义,谢谢!
The son smiled and said, "Father ,I have studied a science which can make me prove that these two chickens in the dish are really three chickens."
"Well ,"said the father ,“this is something I would very much like to know"
“so would I,”said the mother."How can you prove there are three chickens in the dish?"
“Oh, that's not difficult.There are two chickens on the dish,”said the student.He took one of the chickens in his hand and said,“Here is one more;and one and two make three.So here are three chickens.”
最后一个双引号里面的句子在文中是个啥意思啊?

是个笑话
孩子笑着对爸爸说:“爸爸,我通过学科学能证明盘子里的两只鸡其实是三只鸡”
爸爸和妈妈问“你怎么证明呢?我们很好奇”
儿子说“这样, 盘子里有两只鸡”他指着其中一只说“这是第一只”, 指着另外一只说“这是第二只. 一加二等于三. 所以盘子里有三只鸡”