diff --git a/src/basic-syntax/compound-types.md b/src/basic-syntax/compound-types.md
index bf534596..7ad8e25c 100644
--- a/src/basic-syntax/compound-types.md
+++ b/src/basic-syntax/compound-types.md
@@ -24,3 +24,33 @@ fn main() {
     println!("2nd index: {}", t.1);
 }
 ```
+
+<details>
+    
+Key points:
+    
+Arrays:
+    
+*Arrays have elements of the same type, T, and length, N, which is fixed. 
+
+*We can use literals to assign values to arrays.
+
+*Demonstrate out of bounds errors by setting n to different values 
+    e.g. a[n+15] = 11 // index out of bounds error since len is 10
+
+*Efficient way to check n is in bounds:
+    assert!(n+20 < a.len()); // panics
+
+*In the main function, the print statement contains the debug implementation {a :?}.
+
+*Adding #, eg {a:#?}, invokes a "pretty printing" format, which can be easier to read.
+
+Tuples:
+
+*Like arrays, tuples have a fixed length.
+
+*Tuples group together values of different types into a compound type. 
+
+*Fields that can be accessed by the period and the index of the value, e.g. t.0, t.1.
+
+</details>