--- a/ProgTutorial/FirstSteps.thy	Fri Feb 05 15:49:03 2010 +0100
+++ b/ProgTutorial/FirstSteps.thy	Thu Feb 11 10:44:50 2010 +0100
@@ -638,7 +638,7 @@
   These two functions can, for example, be used to avoid explicit @{text "lets"} for
   intermediate values in functions that return pairs. As an example, suppose you
   want to separate a list of integers into two lists according to a
-  treshold. If the treshold is @{ML "5"}, the list @{ML "[1,6,2,5,3,4]"}
+  threshold. If the threshold is @{ML "5"}, the list @{ML "[1,6,2,5,3,4]"}
   should be separated as @{ML "([1,2,3,4], [6,5])"}.  Such a function can be
   implemented as
 *}