copy for day 4

shared/challenges_markdown/four/part_one.md

···
-You may have seen some record keys that look a bit like this `3mhhb2bgzs22p`, these are
-called [TIDs](https://atproto.com/specs/tid), or Timestamp Identifiers. These are the most common record keys. They
-are
-made up of a `clock id` and a `timestamp` then encoded in a way that you can sort and order by time. The clock id helps
-with uniqueness if you are running multiple nodes, and the timestamps are in nanoseconds as well to help with this.
+You may have seen some record keys that look a bit like this: `3mhhb2bgzs22p`.
 
-Today you will be making a `tid` withe clock id of `{{clock_id}}` and a timestamp of `{{tid_time}}`.
+These are [TIDs](https://atproto.com/specs/tid) (Timestamp Identifiers), the most common format for record keys. They are made up of a `timestamp` and a `clock id`, and encoded in a way that you can sort and order by time.
 
-Hint: May check out [@atcute/tid](https://github.com/mary-ext/atcute/tree/trunk/packages/utilities/tid)
+- The timestamp is microcoseconds since the unix epoch.
+- The clock ID is typically randomized, to help avoid collisions across devices.
+
+Your challeng is to **create a `tid`** with:
+
+- **Timestamp**: exactly `{{clock_id}}`
+- **Clock ID**: `{{tid_time}}`
+
+<details>
+  <summary>Hint</summary>
+
+  - In javascript: check out [@atcute/tid](https://github.com/mary-ext/atcute/tree/trunk/packages/utilities/tid)
+</details>