He says they are assessed - which means tested and given scores - when they are seven years old.

他说在这些学生7岁时“测试”他们，也就是对这些学生进行考试然后给出成绩。

That's something that is " tried-and-true." The word " tried" here means tested, or used to make sure that it works.

那是“经过验证” 的东西。 这里的“尝试” 一词意味着经过测试，或用于确保其有效。