diff --git a/README.markdown b/README.markdown
index 27662f5..a108de6 100644
--- a/README.markdown
+++ b/README.markdown
@@ -63,17 +63,20 @@ Ok, have at it!
 * TestSortedCollection
 * TestBag
 * TestAssociation
-\* TestDictionary
+* TestDictionary
 * TestSet
 * TestBlock
 * TestCollectionsRevisited
-\* TestIteration
-\* TestBoolean
-\* TestException
+* TestIteration
+* TestBoolean
+* TestException
 * TestRegex
-\* TestClass
-\* TestClassHierarchy
-\* TestMetaclass
+* TestClass
+
+### Koans that still need to be written
+
+* TestClassHierarchy
+* TestMetaclass
 
 ### Pull Requests and Feedback are Welcome!
 
@@ -91,7 +94,9 @@ There is no set time, but I plan to port these koans over to the following Small
 * redline?
 * Jtalk?
 
-### Credits
+### Inspiration and Credits
+
+GNU Smalltalk Koans were inspired by Edgecase's Ruby Koans and Aaron Bedra's Clojure Koans (now maintained by Colin Jones).
 
 Thanks to [Matt Yoho](http://twitter.com/#!/mattyoho) of the Ruby Koans team for letting me port some of the koans over.
 
diff --git a/src/koans/TestArray.st b/src/koans/TestArray.st
index e802fc7..557807f 100644
--- a/src/koans/TestArray.st
+++ b/src/koans/TestArray.st
@@ -47,7 +47,7 @@ Koan subclass: TestArray [
     array := Array with: 2 with: 4 with: 6 with: 8 with: 10.
 
     self expect: (self fillMeIn) toEqual: (array).
-    self expect: [Array with: 1 with: 3 with: 5 with: 7 with: 9 with: 11] toRaise: (self fillMeIn).
+    self expect: [ Array with: 1 with: 3 with: 5 with: 7 with: 9 with: 11 ] toRaise: (self fillMeIn).
   ]
 
   testReplaceValueAtElement [
@@ -64,7 +64,7 @@ Koan subclass: TestArray [
 
     array := #('a' 'b' 'c').
 
-    self expect: [array at: 1 put: 'd'] toRaise: (self fillMeIn).
+    self expect: [ array at: 1 put: 'd' ] toRaise: (self fillMeIn).
 
     "#() only accepts literal values."
   ]
diff --git a/src/koans/TestAssociation.st b/src/koans/TestAssociation.st
index 3a42419..e723cca 100644
--- a/src/koans/TestAssociation.st
+++ b/src/koans/TestAssociation.st
@@ -1,4 +1,6 @@
 Koan subclass: TestAssociation [
+  <comment: 'A collection of association tests.'>
+
   testCreatingAssociationThreeDifferentWays [
     | association anotherAssociation andAnotherAssociation |
 
diff --git a/src/koans/TestBag.st b/src/koans/TestBag.st
index b1deb18..78e7f8d 100644
--- a/src/koans/TestBag.st
+++ b/src/koans/TestBag.st
@@ -21,7 +21,7 @@ Koan subclass: TestBag [
     bag add: 1 withOccurrences: 3.
     bag add: 2.
 
-    self expect: [bag at: 1] toRaise: (self fillMeIn).
+    self expect: [ bag at: 1 ] toRaise: (self fillMeIn).
   ]
 
   testComparingBags [
diff --git a/src/koans/TestBlock.st b/src/koans/TestBlock.st
index 529b388..5af6e47 100644
--- a/src/koans/TestBlock.st
+++ b/src/koans/TestBlock.st
@@ -66,7 +66,7 @@ Koan subclass: TestBlock [
 
     block := [ :x | x ].
 
-    self expect: [block value: 1 value: 2] toRaise: (self fillMeIn).
+    self expect: [ block value: 1 value: 2 ] toRaise: (self fillMeIn).
   ]
 
   testIterateUsingInterval [
@@ -116,7 +116,7 @@ Koan subclass: TestBlock [
     block := [].
 
     self expect: (self fillMeIn) toEqual: (block cull: 1).
-    self expect: [block value: 1] toRaise: (self fillMeIn).
+    self expect: [ block value: 1 ] toRaise: (self fillMeIn).
   ]
 
   testEachBlockIsAUniqueObject [
diff --git a/src/koans/TestBoolean.st b/src/koans/TestBoolean.st
index d354d54..f54cb57 100644
--- a/src/koans/TestBoolean.st
+++ b/src/koans/TestBoolean.st
@@ -1,17 +1,72 @@
 Koan subclass: TestBoolean [
   <comment: 'A collection of boolean tests.'>
 
-  testIfTrueAndIfFalse [
-    | result anotherResult |
-
-    (1 < 2)
-      ifTrue: [ result := true ]
-      ifFalse: [ result := false ].
-    ((5 + 2 * 9) < 25 )
-      ifTrue: [ anotherResult := true ]
-      ifFalse: [ anotherResult := false ].
-
-    self expect: (self fillMeIn) toEqual: (result).
-    self expect: (self fillMeIn) toEqual: (anotherResult).
+  truthValue: condition [
+    condition ifTrue: [ ^#trueStuff ].
+    condition ifFalse: [ ^#falseStuff ].
+  ]
+
+  testTrueIsTreatedAsTrue [
+    self expect: (self fillMeIn) toEqual: (self truthValue: true).
+  ]
+
+  testFalseIsTreatedAsFalse [
+    self expect: (self fillMeIn) toEqual: (self truthValue: false).
+  ]
+
+  testNilIsNotTreatedAsABoolean [
+    self expect: [ self truthValue: nil ] toRaise: (self fillMeIn).
+  ]
+
+  testIfTrueAndIfFalseOnlyRespondsToBooleans [
+    self expect: [ self truthValue: 1 ] toRaise: (self fillMeIn).
+    self expect: [ self truthValue: 0 ] toRaise: (self fillMeIn).
+    self expect: [ self truthValue: #() ] toRaise: (self fillMeIn).
+    self expect: [ self truthValue: 'String' ] toRaise: (self fillMeIn).
+    self expect: [ self truthValue: '' ] toRaise: (self fillMeIn).
+  ]
+
+  testAndShortCircuit [
+    | x y z |
+
+    x := 4. y := 10. z := 0.
+
+    self expect: (self fillMeIn) toEqual: (x < 5 and: [ z := 1. y < 11 ]).
+    self expect: (self fillMeIn) toEqual: z.
+
+    z := 0.
+
+    self expect: (self fillMeIn) toEqual: (x < 4 and: [ z := 1. y < 11 ]).
+    self expect: (self fillMeIn) toEqual: z.
+
+    "How is this different from '&'?"
+  ]
+
+  testOrShortCircuit [
+    | x y z |
+
+    x := 4. y := 10. z := 0.
+
+    self expect: (self fillMeIn) toEqual: (x > 5 or: [ z := 1. y > 9]).
+    self expect: (self fillMeIn) toEqual: z.
+
+    z := 0.
+
+    self expect: (self fillMeIn) toEqual: (x > 9 sqrt or: [ z := 1. y > 9]).
+    self expect: (self fillMeIn) toEqual: z.
+  ]
+
+  testEqv [
+    self expect: (self fillMeIn) toEqual: (true eqv: true).
+    self expect: (self fillMeIn) toEqual: (true eqv: false).
+    self expect: (self fillMeIn) toEqual: (false eqv: true).
+    self expect: (self fillMeIn) toEqual: (false eqv: false).
+  ]
+
+  testXor [
+    self expect: (self fillMeIn) toEqual: (true xor: true).
+    self expect: (self fillMeIn) toEqual: (true xor: false).
+    self expect: (self fillMeIn) toEqual: (false xor: true).
+    self expect: (self fillMeIn) toEqual: (false xor: false).
   ]
 ]
diff --git a/src/koans/TestClass.st b/src/koans/TestClass.st
index bf7754d..da738af 100644
--- a/src/koans/TestClass.st
+++ b/src/koans/TestClass.st
@@ -1,13 +1,90 @@
-Koan subclass: TestClass [
-  <comment: 'A collection of class tests.'>
+Object subclass: HelloWorld [
+  <comment: 'This is a HelloWorld comment'>
+  <category: 'This is a HelloWorld category'>
+
+  Statement := $S.
+
+  | instanceVariable |
 
   "Unlike other Smalltalks, method statements are inside brackets."
 
-  "Class variables are defined the same as variable assignments."
+  awesome [
+    ^true
+  ]
+
+  + string [
+    ^'Hello ', string
+  ]
 
-  "Pragmas define class comment, class category, imported namespaces, and the shape of indexed instance variables."
+  say: something [
+    ^self class name asString, ' says ', something
+  ]
+]
+
+HelloWorld subclass: SubHelloWorld []
+
+Koan subclass: TestClass [
+  <comment: 'A collection of class tests.'>
+
+  "Class variables are defined the same as variable assignments."
 
   "superclass"
   "allInstances"
   "allSuperclasses"
+
+  testName [
+    self expect: (self fillMeIn) toEqual: HelloWorld name.
+  ]
+
+  testPragmas [
+    "
+    Pragmas define:
+      class comment
+      class category
+      imported namespaces
+      shape of indexed instance variables.
+    "
+
+    self expect: (self fillMeIn) toEqual: HelloWorld comment.
+    self expect: (self fillMeIn) toEqual: HelloWorld category.
+  ]
+
+  testInstanceVariableCollection [
+    self expect: (self fillMeIn) toEqual: HelloWorld instVarNames.
+  ]
+
+  testClassInstanceVariableCollection [
+    self expect: (self fillMeIn) toEqual: HelloWorld classVarNames asArray.
+  ]
+
+  testMessageCollection [
+    self expect: (self fillMeIn) toEqual: HelloWorld selectors asArray.
+  ]
+
+  testSourceCodeAt [
+    "
+    #sourceCodeAt: returns the source code of the specified message.
+    For example: HelloWorld sourceCodeAt: #+ would return:
+
+    '+ string [
+      ^''Hello '', string
+    ]'
+    "
+  ]
+
+  testAllInstances [
+    | helloWorld |
+
+    helloWorld := HelloWorld new.
+
+    self expect: (self fillMeIn) toEqual: (HelloWorld allInstances asArray).
+  ]
+
+  testSuperclass [
+    self expect: (self fillMeIn) toEqual: (HelloWorld superclass).
+  ]
+
+  testAllSubclasses [
+    self expect: (self fillMeIn) toEqual: (HelloWorld allSubclasses asArray).
+  ]
 ]
diff --git a/src/koans/TestClassHierarchy.st b/src/koans/TestClassHierarchy.st
index 786dc76..c78fb14 100644
--- a/src/koans/TestClassHierarchy.st
+++ b/src/koans/TestClassHierarchy.st
@@ -1,6 +1,13 @@
 Koan subclass: TestClassHierarchy [
   <comment: 'A collection of class hierarchy tests.'>
 
+  testSuperclasses [
+    self expect: (self fillMeIn) toEqual: (SmallInteger superclass).
+    self expect: (self fillMeIn) toEqual: (String superclass).
+    self expect: (self fillMeIn) toEqual: (String superclass).
+    self expect: (self fillMeIn) toEqual: (True superclass).
+  ]
+
   testNumberAndMagnitudeAreAbstractClasses [
     self expect: (self fillMeIn) toEqual: (1234 isKindOf: Number).
     self expect: (self fillMeIn) toEqual: (1234 isKindOf: Magnitude).
diff --git a/src/koans/TestCollectionsRevisited.st b/src/koans/TestCollectionsRevisited.st
index 9cf9c11..16b520a 100644
--- a/src/koans/TestCollectionsRevisited.st
+++ b/src/koans/TestCollectionsRevisited.st
@@ -157,7 +157,7 @@ Koan subclass: TestCollectionsRevisited [
     array := #(0 1 2 3).
 
     self expect: (self fillMeIn) toEqual: (array at: 0 ifAbsent: [nil]).
-    self expect: [array at: 0] toRaise: (self fillMeIn).
+    self expect: [ array at: 0 ] toRaise: (self fillMeIn).
 
     "#at:ifAbsent: also works on OrderedCollection, SortedCollection, and Dictionary."
   ]
@@ -168,6 +168,6 @@ Koan subclass: TestCollectionsRevisited [
     orderedCollection := OrderedCollection new addAll: #(0 1 2 3); yourself.
 
     self expect: (self fillMeIn) toEqual: (orderedCollection remove: 4 ifAbsent: [nil]).
-    self expect: [orderedCollection remove: 4] toRaise: (self fillMeIn).
+    self expect: [ orderedCollection remove: 4 ] toRaise: (self fillMeIn).
   ]
 ]
diff --git a/src/koans/TestDictionary.st b/src/koans/TestDictionary.st
index e7651ed..f553a82 100644
--- a/src/koans/TestDictionary.st
+++ b/src/koans/TestDictionary.st
@@ -1,4 +1,6 @@
 Koan subclass: TestDictionary [
+  <comment: 'A collection of dictionary tests.'>
+
   testCreatingANewDictionary [
     | dictionary |
 
@@ -11,13 +13,13 @@ Koan subclass: TestDictionary [
   testAddingKeysAndValuesUsingAssociations [
     | dictionary |
 
-    dictionary := Dictionary new.
-    dictionary
-      add: #a   -> 1;
-      add: 'b'  -> 2;
-      add: 100  -> 3;
-      add: true -> 4;
-      add: nil  -> 5.
+    dictionary := Dictionary new
+                    add: #a   -> 1;
+                    add: 'b'  -> 2;
+                    add: 100  -> 3;
+                    add: true -> 4;
+                    add: nil  -> 5;
+                    yourself.
 
     self expect: (self fillMeIn) toEqual: (dictionary at: #a).
     self expect: (self fillMeIn) toEqual: (dictionary at: 'b').
@@ -29,10 +31,10 @@ Koan subclass: TestDictionary [
   testAddingAssociationsUsingAtPut [
     | dictionary |
 
-    dictionary := Dictionary new.
-    dictionary
-      at: #a put: 1;
-      at: #b put: 2.
+    dictionary := Dictionary new
+                    at: #a put: 1;
+                    at: #b put: 2;
+                    yourself.
 
     self expect: (self fillMeIn) toEqual: (dictionary at: #a).
     self expect: (self fillMeIn) toEqual: (dictionary at: #b).
@@ -65,5 +67,104 @@ Koan subclass: TestDictionary [
     self expect: (self fillMeIn) toEqual: (dictionary values).
     self expect: (self fillMeIn) toEqual: (dictionary keys class).
     self expect: (self fillMeIn) toEqual: (dictionary values class).
+
+    "Why do you think the classes are different?"
+  ]
+
+  testRemoveKey [
+    | dictionary value |
+
+    dictionary := Dictionary new
+                    add: #a -> 1;
+                    add: #b -> 3;
+                    yourself.
+
+    value := dictionary removeKey: #a.
+
+    self expect: (self fillMeIn) toEqual: value.
+    self expect: (self fillMeIn) toEqual: (dictionary keys).
+
+    self expect: [ dictionary removeKey: #c ] toRaise: (self fillMeIn).
+
+    value := dictionary removeKey: #c ifAbsent: [0].
+
+    self expect: (self fillMeIn) toEqual: value.
+  ]
+
+  testIncludesKey [
+    | dictionary |
+
+    dictionary := Dictionary new
+                    add: #daft -> 5;
+                    add: #duck -> 55;
+                    yourself.
+
+    self expect: (self fillMeIn) toEqual: (dictionary includesKey: #daft).
+    self expect: (self fillMeIn) toEqual: (dictionary includesKey: #monk).
+    self expect: (self fillMeIn) toEqual: (dictionary includesKey: 'daft').
+  ]
+
+  testIteratingKeys [
+    | dictionary array counter |
+
+    dictionary := Dictionary new
+                    add: #a -> 2;
+                    add: #c -> 4;
+                    add: #e -> 6;
+                    yourself.
+    array := Array new: dictionary size.
+    counter := 1.
+
+    dictionary keysDo: [ :key |
+      array at: counter put: key.
+      counter := counter + 1.
+    ].
+
+    self expect: (self fillMeIn) toEqual: array.
+  ]
+
+  testIteratingAssociations [
+    | dictionary array counter |
+
+    dictionary := Dictionary new
+                    add: #a -> 1;
+                    add: #b -> 2;
+                    add: #c -> 3;
+                    yourself.
+    array := Array new: dictionary size.
+    counter := 1.
+
+    dictionary associationsDo: [ :association |
+      array at: counter put: association.
+      counter := counter + 1.
+    ].
+    array sort.
+
+    self expect: (self fillMeIn) toEqual: array.
+    "Be careful how you craft the array."
+  ]
+
+  testIteratingKeysAndValues [
+    | dictionary array counter |
+
+    dictionary := Dictionary new
+                    add: #a -> 1;
+                    add: #b -> 2;
+                    add: #c -> 3;
+                    yourself.
+    array := Array new: dictionary size.
+    counter := 1.
+
+    dictionary keysAndValuesDo: [ :key :value |
+      array at: counter put: (key -> value).
+      counter := counter + 1.
+    ].
+
+    self expect: (self fillMeIn) toEqual: array.
+  ]
+
+  testSmalltalkDictionary [
+    self expect: (self fillMeIn) toEqual: (Smalltalk class).
+    self expect: (self fillMeIn) toEqual: (Smalltalk isKindOf: Dictionary).
   ]
 ]
diff --git a/src/koans/TestException.st b/src/koans/TestException.st
index 2e5d38e..d62f3e8 100644
--- a/src/koans/TestException.st
+++ b/src/koans/TestException.st
@@ -1,3 +1,31 @@
 Koan subclass: TestException [
+  <comment: 'A collection of exception tests.'>
 
+  testHaltAndError [
+    self expect: [ self halt ] toRaise: (self fillMeIn).
+    self expect: [ self error: 'Error' ] toRaise: (self fillMeIn).
+
+    "All classes have halt and error messages."
+  ]
+
+  testSignal [
+    self expect: [ Exception signal ] toRaise: (self fillMeIn).
+    self expect: [ Exception signal: 'Hello World' ] toRaise: (self fillMeIn).
+  ]
+
+  testCatchingExceptionsWithOnDo [
+    | result |
+
+    result := [ nil ifTrue: [] ]
+                on: SystemExceptions.MustBeBoolean
+                do: [ :e | e return: true ].
+
+    self expect: (self fillMeIn) toEqual: result.
+
+    result := [ 'Hello' + ' World!' ]
+                on: MessageNotUnderstood
+                do: [ :e | e return: true ].
+
+    self expect: (self fillMeIn) toEqual: result.
+  ]
 ]
diff --git a/src/koans/TestIteration.st b/src/koans/TestIteration.st
index 9d6eb7d..e6174ae 100644
--- a/src/koans/TestIteration.st
+++ b/src/koans/TestIteration.st
@@ -1,3 +1,35 @@
 Koan subclass: TestIteration [
+  <comment: 'A collection of iteration tests.'>
 
+  testWhileTrue [
+    | x y |
+
+    x := 4. y := 1.
+
+    [ x > 0 ] whileTrue: [ x := x - 1. y := y * 2 ].
+
+    self expect: (self fillMeIn) toEqual: y.
+    self expect: (self fillMeIn) toEqual: x.
+  ]
+
+  testWhileFalse [
+    | x y |
+
+    x := 0. y := 1.
+
+    [ x >= 4 ] whileFalse: [ x := x + 1. y := y * 2 ].
+
+    self expect: (self fillMeIn) toEqual: y.
+    self expect: (self fillMeIn) toEqual: x.
+  ]
+
+  testTimesRepeat [
+    | x y |
+
+    x := 4. y := 2.
+
+    x timesRepeat: [ y := y * 2 ].
+
+    self expect: (self fillMeIn) toEqual: y.
+  ]
 ]
diff --git a/src/koans/TestMessage.st b/src/koans/TestMessage.st
index d4d23ad..0301d20 100644
--- a/src/koans/TestMessage.st
+++ b/src/koans/TestMessage.st
@@ -98,7 +98,7 @@ Koan subclass: TestMessage [
 
     self expect: (self fillMeIn) toEqual: value.
 
-    "Think about it: we're sending multiple messages to '3'."
+    "Think about it: we are sending multiple messages to '3'."
   ]
 
   testYourselfIsReferenceToSelf [
@@ -106,12 +106,12 @@ Koan subclass: TestMessage [
 
     "yourself is a reference to self."
 
-    object := OrderedCollection new
-                add: 1;
-                add: 2.
-    anotherObject := OrderedCollection new
-                      add: 1;
-                      add: 2;
+    object := (Array new: 2)
+                at: 1 put: 'a';
+                at: 2 put: 'b'.
+    anotherObject := (Array new: 2)
+                      at: 1 put: 'a';
+                      at: 2 put: 'b';
                       yourself.
 
     self expect: (self fillMeIn) toEqual: (object class).
diff --git a/src/koans/TestNumber.st b/src/koans/TestNumber.st
index 8b1a650..1f86932 100644
--- a/src/koans/TestNumber.st
+++ b/src/koans/TestNumber.st
@@ -32,4 +32,16 @@ Koan subclass: TestNumber [
     self expect: (self fillMeIn) toEqual: (10 min: 5).
     self expect: (self fillMeIn) toEqual: (20 max: 15).
   ]
+
+  testPositiveAndNegative [
+    self expect: (self fillMeIn) toEqual: (5 positive).
+    self expect: (self fillMeIn) toEqual: (-5 negative).
+    self expect: (self fillMeIn) toEqual: (5 strictlyPositive).
+    self expect: (self fillMeIn) toEqual: (0 strictlyPositive).
+  ]
+
+  testEvenAndOdd [
+    self expect: (self fillMeIn) toEqual: (2 even).
+    self expect: (self fillMeIn) toEqual: (1 odd).
+  ]
 ]
diff --git a/src/koans/TestObject.st b/src/koans/TestObject.st
index 520539c..c84d8ba 100644
--- a/src/koans/TestObject.st
+++ b/src/koans/TestObject.st
@@ -16,7 +16,7 @@ Koan subclass: TestObject [
   ]
 
   testNilObjectCannotBeConvertedToString [
-    self expect: [nil asString] toRaise: (self fillMeIn).
+    self expect: [ nil asString ] toRaise: (self fillMeIn).
   ]
 
   testObjectsCanBeInspected [
diff --git a/src/koans/TestOrderedCollection.st b/src/koans/TestOrderedCollection.st
index 4c4b322..14a4ee8 100644
--- a/src/koans/TestOrderedCollection.st
+++ b/src/koans/TestOrderedCollection.st
@@ -21,7 +21,7 @@ Koan subclass: TestOrderedCollection [
     orderedCollection := OrderedCollection with: $a with: $b with: $c with: $d with: $e.
 
     self expect: (self fillMeIn) toEqual: (orderedCollection).
-    self expect: [OrderedCollection with: 'a' with: 'b' with: 'c' with: 'd' with: 'e' with: 'f'] toRaise: (self fillMeIn).
+    self expect: [ OrderedCollection with: 'a' with: 'b' with: 'c' with: 'd' with: 'e' with: 'f' ] toRaise: (self fillMeIn).
 
     "OrderedCollection responds to most messages that Array responds to."
   ]
diff --git a/src/koans/TestString.st b/src/koans/TestString.st
index fc43961..b7dccad 100644
--- a/src/koans/TestString.st
+++ b/src/koans/TestString.st
@@ -26,7 +26,7 @@ Koan subclass: TestString [
     self expect: (self fillMeIn) toEqual: string.
 
     "Concatenation does not quite work this way..."
-    self expect: ['Hello ' + 'World'] toRaise: (self fillMeIn).
+    self expect: [ 'Hello ' + 'World' ] toRaise: (self fillMeIn).
   ]
 
   testStringConcatenationWillLeaveOriginalStringsUnmodified [
@@ -69,7 +69,7 @@ Koan subclass: TestString [
 
     string := 'Smalltalk'.
 
-    self expect: [string copyFrom: 6 to: 10] toRaise: (self fillMeIn).
+    self expect: [ string copyFrom: 6 to: 10 ] toRaise: (self fillMeIn).
   ]
 
   testSingleCharacterFromString [
diff --git a/src/lib/Koan.st b/src/lib/Koan.st
index f80c781..93739de 100644
--- a/src/lib/Koan.st
+++ b/src/lib/Koan.st
@@ -20,15 +20,23 @@ Object subclass: Koan [
   ]
 
   collections [
-    ^{Array . ArrayedCollection . OrderedCollection . SortedCollection . HashCollection . Dictionary . Set . Bag}
+    ^{Array . WeakArray . ArrayedCollection . OrderedCollection . SortedCollection . HashCollection . IdentityDictionary . Dictionary . IdentitySet . Set . Bag}
   ]
 
   zenMessage [
     ^'@dhh > Whoops!'
   ]
 
+  className: value [
+    ^value class name asString
+  ]
+
+  anInstanceOf: value [
+    ^' (an instance of ', (self className: value), ')'
+  ]
+
   prettify: value [
-    | prettyValue |
+    | message |
 
     (value = self fillMeIn)
       ifTrue: [ ^value ].
@@ -42,11 +50,12 @@ Object subclass: Koan [
       ].
     (value class = Character)
       ifTrue: [
-        ^'$', value asString, ' (an instance of ', value class name, ')'
+        ^'$', value asString, ' ', (self anInstanceOf: value)
       ].
     (self collections includes: (value class))
       ifTrue: [
-        ^'#', value displayString, ' (an instance of ', value class name, ')'
+        message := value displayString replacingRegex: ((self className: value), ' ') with: ''.
+        ^message, (self anInstanceOf: value)
       ].
     (Exception allSubclasses asArray includes: value)
       ifTrue: [
@@ -58,9 +67,9 @@ Object subclass: Koan [
       ].
     (value respondsTo: #asString)
       ifTrue: [
-        ^value asString, ' (an instance of ', value class name, ')'
+        ^value asString, ' ', (self anInstanceOf: value)
       ].
-    ^'(an instance of ', value class name, ')'
+    ^self anInstanceOf: value
   ]
 
   diff [
diff --git a/src/lib/Zen.st b/src/lib/Zen.st
index 154a2eb..67948e9 100644
--- a/src/lib/Zen.st
+++ b/src/lib/Zen.st
@@ -38,7 +38,7 @@ Object subclass: Zen [
     self testBoolean.
     self testException.
     self testRegex.
-    self testClass.          "inheritance, cool methods"
+    self testClass.
     self testClassHierarchy.
     self testMetaclass.      "metaprogramming"
 
@@ -106,6 +106,8 @@ Object subclass: Zen [
     self tally: #testNegation.
     self tally: #testRounding.
     self tally: #testMinMaxOfTwoNumbers.
+    self tally: #testPositiveAndNegative.
+    self tally: #testEvenAndOdd.
   ]
 
   testString [
@@ -201,6 +203,12 @@ Object subclass: Zen [
     self tally: #testAddingAssociationsUsingAtPut.
     self tally: #testReplaceValueAtKey.
     self tally: #testRetrievingCollectionOfKeysAndValues.
+    self tally: #testRemoveKey.
+    self tally: #testIncludesKey.
+    self tally: #testIteratingKeys.
+    self tally: #testIteratingAssociations.
+    self tally: #testIteratingKeysAndValues.
+    self tally: #testSmalltalkDictionary.
   ]
 
   testSet [
@@ -244,15 +252,28 @@ Object subclass: Zen [
 
   testIteration [
      currentTest := TestIteration create: (self tracker).
+     self tally: #testWhileTrue.
+     self tally: #testWhileFalse.
+     self tally: #testTimesRepeat.
   ]
 
   testBoolean [
     currentTest := TestBoolean create: (self tracker).
-    self tally: #testIfTrueAndIfFalse.
+    self tally: #testTrueIsTreatedAsTrue.
+    self tally: #testFalseIsTreatedAsFalse.
+    self tally: #testNilIsNotTreatedAsABoolean.
+    self tally: #testIfTrueAndIfFalseOnlyRespondsToBooleans.
+    self tally: #testAndShortCircuit.
+    self tally: #testOrShortCircuit.
+    self tally: #testEqv.
+    self tally: #testXor.
   ]
 
   testException [
     currentTest := TestException create: (self tracker).
+    self tally: #testHaltAndError.
+    self tally: #testSignal.
+    self tally: #testCatchingExceptionsWithOnDo.
   ]
 
   testRegex [
@@ -291,6 +312,14 @@ Object subclass: Zen [
 
   testClass [
     currentTest := TestClass create: (self tracker).
+    self tally: #testName.
+    self tally: #testPragmas.
+    self tally: #testInstanceVariableCollection.
+    self tally: #testClassInstanceVariableCollection.
+    self tally: #testMessageCollection.
+    self tally: #testAllInstances.
+    self tally: #testSuperclass.
+    self tally: #testAllSubclasses.
   ]
 
   testClassHierarchy [