diff --git a/src/teaching/cse-562/2019sp/index.erb b/src/teaching/cse-562/2019sp/index.erb
index 3a826497..d54bda22 100644
--- a/src/teaching/cse-562/2019sp/index.erb
+++ b/src/teaching/cse-562/2019sp/index.erb
@@ -38,6 +38,8 @@ schedule:
     due: "Homework 1"
     topic: "Extended Relational Algebra"
     textbook: "Ch. 5.2, 15.4"
+    materials:
+      slides: "slide/2019-02-13-ExtRA.html"
   - date: "Feb 15"
     topic: "Physical Data Layout"
     note: Serialization, Paging, Columnar, Buffer Manager