diff --git a/src/tuples-and-arrays.md b/src/tuples-and-arrays.md
index 675851ba..0a831020 100644
--- a/src/tuples-and-arrays.md
+++ b/src/tuples-and-arrays.md
@@ -1,3 +1,10 @@
 # Tuples and Arrays
 
 {{%segment outline}}
+
+<details>
+
+- We have seen how primitive types work in Rust. Now it's time for you to start
+  building new composite types.
+
+</details>