Instead of submitting a copy of your teaching certificate with your application, you may submit verification that you are matriculated in a certification program (e.g., letter of acceptance, letter from advisor).
Expository writing is writing that seeks to explain, illuminate or 'expose' (which is where the word 'expository' comes from). This type of writing can include essays, newspaper and magazine articles, instruction manuals, textbooks, encyclopedia articles and other forms of writing, so long as they seek to explain.
Expository preaching is a form of preaching that details the meaning of a particular text or passage of Scripture. It explains what the Bible means by what it says. Exegesis is technical and grammatical exposition, a careful drawing out of the exact meaning of a passage in its original context.