Lesson Link: https://tour.json-schema.org/content/07-Miscellaneous/01-Extending-Closed-Schemas-with-unevaluatedProperties

The "Extending Closed Schemas" lesson uses allOf for the example, which is fine, but it's not a normal case. In a previous lesson, you specify that you've make available a schema with a certain URI that you want the user to reference. This would be a great time to employ that technique. You provide an address schema at https://example.com/address and then have then extend it by adding the type property.

{
  "$ref": "https://example.com/address",
  "properties": {
    "type": { "enum": [ "residential", "business" ] }
  },
  "unevaluatedProperties": false,
  "required": ["type"]
}

This is a much more realistic way to show what this keyword is good for.

(Also, I think the unevaluatedItems should look a lot like this lesson except for arrays instead of objects.)