Questions & Answers about Ich schreibe mir eine Notiz dazu.
Mir is the dative form of ich, and mich is the accusative form.
In this sentence there are two “receivers” of the action:
- the note = direct object → accusative
- to/for myself = indirect object → dative
So you get:
- eine Notiz → accusative (what am I writing?)
- mir → dative (to/for whom am I writing it?)
German often uses a dative pronoun to express “to myself / for myself”:
- Ich koche mir einen Kaffee. – I’m making (for myself) a coffee.
- Ich kaufe mir ein neues Handy. – I’m buying myself a new phone.
- Ich schreibe mir eine Notiz. – I’m writing myself a note.
Using mich here would be ungrammatical: *Ich schreibe mich eine Notiz is wrong.