diff --git a/notes-and-examples/2026.08.27/classes.png b/notes-and-examples/2026.08.27/classes.png
index 8ca3fbc..735b601 100644
Binary files a/notes-and-examples/2026.08.27/classes.png and b/notes-and-examples/2026.08.27/classes.png differ
diff --git a/notes-and-examples/2026.08.27/topological_sort.md b/notes-and-examples/2026.08.27/topological_sort.md
index eeca5ac..be6ca62 100644
--- a/notes-and-examples/2026.08.27/topological_sort.md
+++ b/notes-and-examples/2026.08.27/topological_sort.md
@@ -3,9 +3,12 @@
 These are some classes for Chapman University, for
 the [computer science program](https://catalog.chapman.edu/preview_program.php?catoid=33&poid=6408&print).
 
-![An ordering of classes for Chapman University.](classes.png)
+![An ordering of classes for Chapman University.](./classes.png)
 
-> [!QUESTION] What type of graph is this?
+This is a *directed acyclic graph*, or DAG.
+
+- Directed: edges point from one node to another, not necessarily the other way around
+- Acyclic: there are no *cycles* in the graph
 
 We say that a class is a *prerequisite* or a *dependency* of another class
 if we need to take it before that other class. So, we need to take CPSC 230