Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/ChosenGrouper.java
===================================================================
diff -u -rdfed139a7289e34015731c0b41b2435a0b902b6f -r51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/ChosenGrouper.java	(.../ChosenGrouper.java)	(revision dfed139a7289e34015731c0b41b2435a0b902b6f)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/ChosenGrouper.java	(.../ChosenGrouper.java)	(revision 51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12)
@@ -22,6 +22,7 @@
 
 package org.lamsfoundation.lams.learningdesign;
 
+import java.io.Serializable;
 import java.util.List;
 
 import org.lamsfoundation.lams.usermanagement.User;
@@ -34,7 +35,7 @@
  * @version
  * 
  */
-public class ChosenGrouper implements Grouper
+public class ChosenGrouper implements Grouper,Serializable
 {
 
     /**
Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/RandomGrouper.java
===================================================================
diff -u -rdfed139a7289e34015731c0b41b2435a0b902b6f -r51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/RandomGrouper.java	(.../RandomGrouper.java)	(revision dfed139a7289e34015731c0b41b2435a0b902b6f)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/RandomGrouper.java	(.../RandomGrouper.java)	(revision 51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12)
@@ -22,6 +22,7 @@
 
 package org.lamsfoundation.lams.learningdesign;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -55,7 +56,7 @@
  * @version 1.1
  * 
  */
-public class RandomGrouper implements Grouper
+public class RandomGrouper implements Grouper , Serializable
 {
     //---------------------------------------------------------------------
     // Grouping algorithm Implementation Method
Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/strategy/SimpleActivityStrategy.java
===================================================================
diff -u -rcea596d200043c5589e5501fd9d65147091f8014 -r51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/strategy/SimpleActivityStrategy.java	(.../SimpleActivityStrategy.java)	(revision cea596d200043c5589e5501fd9d65147091f8014)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/strategy/SimpleActivityStrategy.java	(.../SimpleActivityStrategy.java)	(revision 51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12)
@@ -6,6 +6,8 @@
  */
 package org.lamsfoundation.lams.learningdesign.strategy;
 
+import java.io.Serializable;
+
 import org.lamsfoundation.lams.learningdesign.Activity;
 
 
@@ -17,7 +19,7 @@
  * TODO To change the template for this generated type comment go to
  * Window - Preferences - Java - Code Style - Code Templates
  */
-public abstract class SimpleActivityStrategy {
+public abstract class SimpleActivityStrategy implements Serializable {
 	
 	public static final int MODERATION = 1;
 	public static final int DEFINE_LATER = 2;
Index: lams_common/src/java/org/lamsfoundation/lams/lesson/ActivityStrategy.java
===================================================================
diff -u -r0cd6d5f3a368eb1fa3a140d87b5b1664ee4aa88d -r51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12
--- lams_common/src/java/org/lamsfoundation/lams/lesson/ActivityStrategy.java	(.../ActivityStrategy.java)	(revision 0cd6d5f3a368eb1fa3a140d87b5b1664ee4aa88d)
+++ lams_common/src/java/org/lamsfoundation/lams/lesson/ActivityStrategy.java	(.../ActivityStrategy.java)	(revision 51d9b7fc27684748ffcd792f6ce6e4f23ef6ce12)
@@ -20,6 +20,7 @@
  */
 package org.lamsfoundation.lams.lesson;
 
+import java.io.Serializable;
 import java.util.Iterator;
 
 import org.lamsfoundation.lams.learningdesign.Activity;
@@ -35,7 +36,7 @@
  * @author Jacky Fang 2005-2-23
  * 
  */
-public abstract class ActivityStrategy
+public abstract class ActivityStrategy implements Serializable
 {
     /**
      * <p>Check up all children completion status for a complex activity. </p>