整理 A いろいろな働きをする助詞 教科書 p.58
Multi-function auxiliary words
接続：N + さえ
even. Give extreme examples to infer other cases.
注意 / Note：Check the correct front form, subject and level of politeness; Don't just translate word for word.
比較 / Compare：Compare with structures in the same lesson to choose according to function in the whole sentence. Same 課: 〜こそ／〜でも／〜も／〜まで／〜くらい／〜ぐらい／〜など／〜なんか／〜だけ — these models are often mistaken for each other, read the 接続 line carefully and then decide.
彼は自分の名前さえ書けません。
That person can't even write his name.
忙しくて昼ご飯さえ食べられませんでした。
So busy that I didn't even eat lunch.
子どもでさえ知っています。
Even children know.