Question on German grammar
Do you capitalize 'I' in a sentence?
You do not. In German, the first letter of the first word in a sentence is capitalized, and all nouns are capitalized.
Most often you encounter the pronoun ich. It won't be capitalized unless at the start of a question.
However, there's this rare abstract word das Ich. English adopted the word the Überich. Das Ich is a noun. It will be capitalized.