diff --git a/notebooks/index.clj b/notebooks/index.clj
index fc05749..3117c78 100644
--- a/notebooks/index.clj
+++ b/notebooks/index.clj
@@ -3511,7 +3511,7 @@ Let's see how many values are for each type of `wool` and `tension` groups
 
 
 (md "
-We can also calculate mean (aggreate values)
+We can also calculate mean (aggregate values)
 ")