diff --git a/assign7.md b/assign7.md
index 40a05ab3f97034221f1cf4ce4ce1a56a129c3bf5..fd734cbc865a4d967b76d5a628366303f3b238f7 100644
--- a/assign7.md
+++ b/assign7.md
@@ -8,6 +8,10 @@ re-execution, *compensating log records*, etc.
 
 Be sure to write back all modified values.
 
+### OPTIONAL Assignment
+You will not get graded as such. If you do the assignment and score well you can replace any other assignment score. To do this you must **email me before 12/11 midnight** me telling me which assignment you'd like to replace. If I do not receive email, I will not make any other changes.
+
+This grade replacement is only for assignments, not homeworks or extra credit on exams.
 
 ### Setup