学 - study
字 - character
So the author actually meant boring teaching of 'characters' with the section on 字 but I don't think it came across well.
THIS ARTICLE IS SO WRONG!
学 is actually the simplified version of the character 學. And the character 子 in both of these characters doesn't really have much connections
The character 子 (literally means children) in 學 stands for "student", but in 字 it is just a rebus (phonetic loan) character.
字 means "characters"