diff --git a/chapter02/worksheets/Example2.2.5.6.scala b/chapter02/worksheets/Example2.2.5.6.scala
index 523200a..3e09d81 100644
--- a/chapter02/worksheets/Example2.2.5.6.scala
+++ b/chapter02/worksheets/Example2.2.5.6.scala
@@ -5,15 +5,15 @@ Implement a function toPairs that converts a sequence of type
 Seq[A] to a sequence of pairs, Seq[(A, A)], by putting together the adjacent elements pairwise. If the initial sequence has an odd number of elements, a given
 default value of type A is used to fill the last pair. The required type signature and
 an example test:
-  */
 
-// def toPairs[A](xs: Seq[A], default: A): Seq[(A, A)] = ???
+def toPairs[A](xs: Seq[A], default: A): Seq[(A, A)] = ???
 
-// scala> toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
-// res0: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+scala> toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+res0: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
 
-// scala> toPairs(Seq("a", "b", "c"), "<nothing>")
-// res1: Seq[(String, String)] = List((a,b), (c,<nothing>))
+scala> toPairs(Seq("a", "b", "c"), "<nothing>")
+res1: Seq[(String, String)] = List((a,b), (c,<nothing>))
+  */
 
 def toPairs[A](xs: Seq[A], default: A): Seq[(A, A)] = {
   type Acc = (Seq[(A, A)], Seq[A])
@@ -34,6 +34,11 @@ def toPairs[A](xs: Seq[A], default: A): Seq[(A, A)] = {
     }
 }
 
-val a =  toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
-println("a: %s".format(a))
-// 
+val result = toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+val expected: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+assert(result == expected) 
+
+val a = toPairs(Seq("a", "b", "c"), "<nothing>")
+val b: Seq[(String, String)] = List(("a","b"), ("c","<nothing>"))
+assert(a == b) 
+
diff --git a/chapter02/worksheets/Example2.2.5.6_object.scala b/chapter02/worksheets/Example2.2.5.6_object.scala
index efcb77b..42865f6 100644
--- a/chapter02/worksheets/Example2.2.5.6_object.scala
+++ b/chapter02/worksheets/Example2.2.5.6_object.scala
@@ -5,6 +5,14 @@ Implement a function toPairs that converts a sequence of type
 Seq[A] to a sequence of pairs, Seq[(A, A)], by putting together the adjacent elements pairwise. If the initial sequence has an odd number of elements, a given
 default value of type A is used to fill the last pair. The required type signature and
 an example test:
+
+def toPairs[A](xs: Seq[A], default: A): Seq[(A, A)] = ???
+
+scala> toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+res0: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+
+scala> toPairs(Seq("a", "b", "c"), "<nothing>")
+res1: Seq[(String, String)] = List((a,b), (c,<nothing>))
   */
 
 object ToPairsObject {
@@ -32,11 +40,10 @@ object ToPairsObject {
   }
 }
 
-val a = ToPairsObject.toPairs(Seq(1, 2, 3), 4)
-println("a: %s".format(a))
+val result = toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+val expected: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+assert(result == expected) 
 
-// scala> :load Example2.2.5.6_object.scala
-// :load Example2.2.5.6_object.scala
-// a: List((1,2), (3,4))
-// // defined object ToPairsObject
-// val a: Seq[(Int, Int)] = List((1,2), (3,4))
+val a = toPairs(Seq("a", "b", "c"), "<nothing>")
+val b: Seq[(String, String)] = List(("a","b"), ("c","<nothing>"))
+assert(a == b) 
diff --git a/chapter02/worksheets/Example2.2.5.6_object_main.scala b/chapter02/worksheets/Example2.2.5.6_object_main.scala
index e016037..423b5ab 100644
--- a/chapter02/worksheets/Example2.2.5.6_object_main.scala
+++ b/chapter02/worksheets/Example2.2.5.6_object_main.scala
@@ -5,6 +5,14 @@ Implement a function toPairs that converts a sequence of type
 Seq[A] to a sequence of pairs, Seq[(A, A)], by putting together the adjacent elements pairwise. If the initial sequence has an odd number of elements, a given
 default value of type A is used to fill the last pair. The required type signature and
 an example test:
+
+def toPairs[A](xs: Seq[A], default: A): Seq[(A, A)] = ???
+
+scala> toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+res0: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+
+scala> toPairs(Seq("a", "b", "c"), "<nothing>")
+res1: Seq[(String, String)] = List((a,b), (c,<nothing>))
   */
 
 object ToPairsObject {
@@ -36,3 +44,11 @@ object ToPairsObject {
     println("a: %s".format(a))
   }
 }
+
+val result = toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+val expected: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+assert(result == expected) 
+
+val a = toPairs(Seq("a", "b", "c"), "<nothing>")
+val b: Seq[(String, String)] = List(("a","b"), ("c","<nothing>"))
+assert(a == b) 
diff --git a/chapter02/worksheets/Example2.2.5.6_object_main_privat.scala b/chapter02/worksheets/Example2.2.5.6_object_main_privat.scala
index 458f89a..203a72e 100644
--- a/chapter02/worksheets/Example2.2.5.6_object_main_privat.scala
+++ b/chapter02/worksheets/Example2.2.5.6_object_main_privat.scala
@@ -5,6 +5,14 @@ Implement a function toPairs that converts a sequence of type
 Seq[A] to a sequence of pairs, Seq[(A, A)], by putting together the adjacent elements pairwise. If the initial sequence has an odd number of elements, a given
 default value of type A is used to fill the last pair. The required type signature and
 an example test:
+
+def toPairs[A](xs: Seq[A], default: A): Seq[(A, A)] = ???
+
+scala> toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+res0: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+
+scala> toPairs(Seq("a", "b", "c"), "<nothing>")
+res1: Seq[(String, String)] = List((a,b), (c,<nothing>))
   */
 
 object ToPairsObject {
@@ -32,8 +40,16 @@ object ToPairsObject {
 
   }
   def main(args: Array[String]): Unit = {
-    val a = ToPairsObject.toPairs(Seq(1, 2, 3), 4)
+    val result = ToPairsObject.toPairs(Seq(1, 2, 3), 4)
+    assert(result == expected) 
     println("a: %s".format(a))
   }
 }
 
+val result = toPairs(Seq(1, 2, 3, 4, 5, 6), -1)
+val expected: Seq[(Int, Int)] = List((1,2), (3,4), (5,6))
+assert(result == expected) 
+
+val a = toPairs(Seq("a", "b", "c"), "<nothing>")
+val b: Seq[(String, String)] = List(("a","b"), ("c","<nothing>"))
+assert(a == b)