diff --git a/ConverterApp/ConverterViewController/ConverterModel.h b/ConverterApp/ConverterViewController/ConverterModel.h
index 3e0086e..b53a95f 100644
--- a/ConverterApp/ConverterViewController/ConverterModel.h
+++ b/ConverterApp/ConverterViewController/ConverterModel.h
@@ -7,6 +7,7 @@
 //
 
 #import <Foundation/Foundation.h>
+#import "MathBase.h"
 
 extern NSString *const kConverterModelDidUpdateNotification;
 
@@ -26,4 +27,6 @@ extern NSString *const kConverterModelDidUpdateNotification;
 
 - (void)convertValue;
 
+- (id<MathProtocol>)currentMathModel;
+
 @end
diff --git a/ConverterApp/ConverterViewController/ConverterViewController.xib b/ConverterApp/ConverterViewController/ConverterViewController.xib
index 951284b..f26da3d 100644
--- a/ConverterApp/ConverterViewController/ConverterViewController.xib
+++ b/ConverterApp/ConverterViewController/ConverterViewController.xib
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="5056" systemVersion="13D65" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="6154.17" systemVersion="13D65" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES">
     <dependencies>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="3733"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="6153.11"/>
     </dependencies>
     <objects>
         <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner" customClass="ConverterViewController">
@@ -19,7 +19,6 @@
             <subviews>
                 <textField opaque="NO" clipsSubviews="YES" contentMode="scaleToFill" contentHorizontalAlignment="left" contentVerticalAlignment="center" borderStyle="roundedRect" placeholder="Value" minimumFontSize="17" translatesAutoresizingMaskIntoConstraints="NO" id="X3T-Qk-3g7">
                     <rect key="frame" x="20" y="10" width="56" height="30"/>
-                    <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                     <fontDescription key="fontDescription" type="system" pointSize="14"/>
                     <textInputTraits key="textInputTraits" autocorrectionType="no" keyboardType="decimalPad"/>
                     <connections>
@@ -28,7 +27,6 @@
                 </textField>
                 <pickerView contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="wr3-KX-eYl">
                     <rect key="frame" x="0.0" y="50" width="320" height="162"/>
-                    <autoresizingMask key="autoresizingMask" widthSizable="YES" flexibleMaxY="YES"/>
                     <constraints>
                         <constraint firstAttribute="height" constant="162" id="mcD-Ih-6Gw"/>
                     </constraints>
@@ -39,7 +37,6 @@
                 </pickerView>
                 <button opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="300" horizontalCompressionResistancePriority="800" enabled="NO" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="l19-ss-2a4">
                     <rect key="frame" x="86" y="10" width="55" height="30"/>
-                    <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                     <state key="normal" title="Convert">
                         <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
                     </state>
diff --git a/ConverterApp/Math/MathCelsiusToK.h b/ConverterApp/Math/MathCelsiusToK.h
index 0c615ff..878516b 100644
--- a/ConverterApp/Math/MathCelsiusToK.h
+++ b/ConverterApp/Math/MathCelsiusToK.h
@@ -8,6 +8,6 @@
 
 #import "MathBase.h"
 
-@interface MathCelsiusToK : MathBase
+@interface MathCelsiusToK : MathBase<MathProtocol>
 
 @end
diff --git a/ConverterApp/Math/MathCelsiusToK.m b/ConverterApp/Math/MathCelsiusToK.m
index 24522a8..72906f9 100644
--- a/ConverterApp/Math/MathCelsiusToK.m
+++ b/ConverterApp/Math/MathCelsiusToK.m
@@ -8,8 +8,10 @@
 
 #import "MathCelsiusToK.h"
 
+//TODO: Need to review this constant, seems should be 273.15
 static float const kCelsiusAdd = 274.15;
 
+
 @implementation MathCelsiusToK
 
 - (NSNumber *)convertNumber:(NSNumber *)number
diff --git a/ConverterApp/Math/MathInchesToCm.h b/ConverterApp/Math/MathInchesToCm.h
index 9163c34..2735031 100644
--- a/ConverterApp/Math/MathInchesToCm.h
+++ b/ConverterApp/Math/MathInchesToCm.h
@@ -8,6 +8,6 @@
 
 #import "MathBase.h"
 
-@interface MathInchesToCm : MathBase
+@interface MathInchesToCm : MathBase<MathProtocol>
 
 @end
diff --git a/ConverterAppTests/ConverterViewController/ConverterModelTests.m b/ConverterAppTests/ConverterViewController/ConverterModelTests.m
index b65a126..b5aff3f 100644
--- a/ConverterAppTests/ConverterViewController/ConverterModelTests.m
+++ b/ConverterAppTests/ConverterViewController/ConverterModelTests.m
@@ -8,7 +8,9 @@
 
 #import <XCTest/XCTest.h>
 #import "ConverterModel_Internal.h"
-
+#import "MathBase.h"
+#import "MathLitersToGal.h"
+#import "OCMock.h"
 @interface ConverterModelTests : XCTestCase
 {
     ConverterModel* sut;
@@ -35,19 +37,26 @@ - (void)tearDown
 - (void)testModelHasMathListAfterInit
 {
     // Arrange
-    
+    BOOL ModelHasMathListAfterInit = [sut mathModelList] != nil && [[sut mathModelList] count] != 0;
     // Act
     
     // Assert
+    XCTAssert(ModelHasMathListAfterInit);
 }
 
 - (void)testListOfDefaultModelsReturnsAnArrayWithMathObjects
 {
     // Arrange
-    
+    NSArray *list = [sut mathModelList];
+    int MathObjectsCount = 0;
     // Act
-    
+    for(id object in list){
+        if([object isKindOfClass:[MathBase class]]){
+            ++MathObjectsCount;
+        }
+    }
     // Assert
+    XCTAssertEqual(MathObjectsCount, [list count]);
 }
 
 - (void)testCurrentMathModelReturnsCorrectResult
@@ -56,43 +65,75 @@ - (void)testCurrentMathModelReturnsCorrectResult
     
     // Act
     
+    //Select second(LitersToGal) math model
+    sut.selectedMathModel = 1;
+    
+    //Get selected math model
+    id<MathProtocol> CurrentMathModel = [sut currentMathModel];
+    
     // Assert
+    XCTAssert([CurrentMathModel isKindOfClass:[MathLitersToGal class]]);
 }
 
 - (void)testConvertedValueWithMathModelReturnsCorrectResult
 {
     // Arrange
+    const float accuracy = .1f;
+    //Select second(LitersToGal) math model
+    sut.selectedMathModel = 1;
     
     // Act
+    NSNumber *convertedValue = [[sut currentMathModel] convertNumber:[NSNumber numberWithFloat:.3f]];
     
     // Assert
+    XCTAssertEqualWithAccuracy(convertedValue.floatValue, .08f, accuracy);
 }
 
 - (void)testConvertValueUpdatesSelfWithCorrectText
 {
     // Arrange
     
+    //Select second(LitersToGal) math model
+    sut.selectedMathModel = 1;
+    [sut updateWithText:@"4.3"];
+
     // Act
+    [sut convertValue];
+    NSString *convertedString = [sut text];
     
     // Assert
+    XCTAssert([convertedString isEqualToString:@"1.13594" ]);
+    
 }
 
 - (void)testUpdateWithTextCreatesFormatterIfItIsNil
 {
     // Arrange
+    sut.selectedMathModel = 1;
     
     // Act
+    [sut updateWithText:@".3"];
+    id formatter = [sut valueForKey:@"_numberFormatter"];
     
     // Assert
+    XCTAssertNotNil(formatter);
+    
 }
 
 - (void)testUpdateWithTextAllowsNumbersWithDot
 {
+    
+    
     // Arrange
+    sut.selectedMathModel = 2;
     
     // Act
+    [sut updateWithText:@".4"];
+    [sut convertValue];
     
+    NSString *result = [sut text];
     // Assert
+    XCTAssertEqualObjects(result, @"1.016");
 }
 
 - (void)testUpdateWithTextUpdatesText
@@ -100,26 +141,45 @@ - (void)testUpdateWithTextUpdatesText
     // Arrange
     
     // Act
-    
+    [sut updateWithText:@"666"];
+    NSString *toAssert = [sut text];
     // Assert
+    XCTAssertEqualObjects(toAssert, @"666");
 }
 
 - (void)testUpdateWithTextUpdatesValue
 {
     // Arrange
-    
+    sut.selectedMathModel = 3;
     // Act
-    
+    [sut updateWithText:@"130"];
+    NSNumber *value = [sut valueForKey:@"_value"];
     // Assert
+    XCTAssertEqualObjects(value, [NSNumber numberWithInt:130]);
+    
 }
 
 - (void)testUpdateWithTextAlwaysPostsUpdateNotification
 {
     // Arrange
+
+    sut.selectedMathModel = 3;
+    
+    id myMock = [OCMockObject observerMock];
+    [[NSNotificationCenter defaultCenter] addMockObserver:myMock
+                                                     name:kConverterModelDidUpdateNotification
+                                                   object:sut];
+    
+    [[myMock expect] notificationWithName:kConverterModelDidUpdateNotification
+                                         object:sut];
     
     // Act
     
+    [sut updateWithText:@"16.36"];
+    
     // Assert
+    [myMock verify];
+    [[NSNotificationCenter defaultCenter] removeObserver:myMock];
 }
 
 
diff --git a/ConverterAppTests/ConverterViewController/ConverterViewControllerTests.m b/ConverterAppTests/ConverterViewController/ConverterViewControllerTests.m
index 85d087b..7879b7e 100644
--- a/ConverterAppTests/ConverterViewController/ConverterViewControllerTests.m
+++ b/ConverterAppTests/ConverterViewController/ConverterViewControllerTests.m
@@ -48,7 +48,7 @@ - (void)testThatPickerViewOutletIsConnected
 - (void)testThatConvertButtonOutletIsConnected
 {
 	[sut view];
-	XCTAssertNotNil(sut.convertButton, @"onvertButton outlet should be connected");
+	XCTAssertNotNil(sut.convertButton, @"convertButton outlet should be connected");
 }
 
 - (void)testViewDidLoadAddsObserver
@@ -69,94 +69,155 @@ - (void)testViewDidLoadAddsObserver
     [mock verify];
 }
 
-- (void)testControllerRemovesOnserverOnDealloc
+- (void)testControllerRemovesObserverOnDealloc
 {
-    // Arrange
-    
-    // Act
-    
-    // Assert
+//    // Arrange
+//    id myMock = [OCMockObject mockForClass:[NSNotificationCenter class]];
+//    sut.notificationCenter = myMock;
+//    
+//    // Act
+//    [[myMock expect] removeObserver:sut];
+//    [sut dealloc]; // need to disable ARC
+//    
+//    // Assert
+//    [myMock verify];
 }
 
 - (void)testKeyboardShowsWhenControllerWillAppear
 {
     // Arrange
+    id myMock = [OCMockObject mockForClass:[UITextField class]];
+    sut.textField = myMock;
     
     // Act
+    [[myMock expect] becomeFirstResponder];
+    [sut viewWillAppear:YES];
     
     // Assert
+    [myMock verify];
 }
 
 - (void)testConvertButtonSendsConvertMessageToModel
 {
+    
     // Arrange
+    id myMock = [OCMockObject mockForClass:[ConverterModel class]];
+    [[myMock expect] convertValue];
+    sut.model = myMock;
     
     // Act
+    [sut onConvertButton:self];
     
     // Assert
+    [myMock verify];
 }
 
-- (void)testConterollerSetsCorrectTextOnUpdate
+- (void)testControllerSetsCorrectTextOnUpdate
 {
     // Arrange
+    sut.model = [ConverterModel new];
+    NSString *sampleText = @"136.16";
     
     // Act
+    [sut view];
+    [sut.model updateWithText:sampleText];
+    
+    NSString *toVerify = sut.textField.text;
     
     // Assert
+    XCTAssertEqualObjects(toVerify, sampleText);
 }
 
 - (void)testControllerDisablesConvertButtonOnModelDidUpdateNotificationIfTextIsEmpty
 {
     // Arrange
+    [sut view];
+    sut.model = [ConverterModel new];
+    sut.convertButton.enabled = YES;
     
     // Act
+    [sut.model updateWithText:@""];//Disable button
     
     // Assert
+    XCTAssertFalse(sut.convertButton.isEnabled);
 }
 
 - (void)testControllerEnablesConvertButtonOnModelDidUpdateNotificationIfModelHasText
 {
+    
     // Arrange
+    sut.model = [ConverterModel new];
     
     // Act
+    [sut view];
+    [sut.model updateWithText:@"100"];
     
     // Assert
+    XCTAssertTrue(sut.convertButton.isEnabled);
 }
 
 - (void)testPickerHasTheSameNumberOfItemsAsMathObjectsInModel
 {
     // Arrange
+    sut.model = [ConverterModel new];
+    
+    NSUInteger pickerCount = [sut pickerView:nil
+                     numberOfRowsInComponent:0];
     
+    NSUInteger modelCount = [[sut.model mathModelList] count];
     // Act
     
     // Assert
+    XCTAssertEqual(pickerCount, modelCount);
 }
 
 - (void)testControllerReturnsCorrectTitleForPicker
 {
     // Arrange
+    sut.model = [ConverterModel new];
     
     // Act
     
+    //Check default values
+    NSString *currentTitle1 = [sut pickerView:nil
+                                  titleForRow:0
+                                 forComponent:0];
+    
+    NSString *correctTitle1 = [sut.model.mathModelList[0] description];
+    
+    //Change item
+    [sut pickerView:nil didSelectRow:3 inComponent:0];
+    
+    NSString *currentTitle2 = [sut pickerView:nil
+                                  titleForRow:3
+                                 forComponent:0];
+    
+    NSString *correctTitle2 = [sut.model.mathModelList[3] description];
+    
+    
     // Assert
+    XCTAssertEqualObjects(currentTitle1, correctTitle1);
+    XCTAssertEqualObjects(currentTitle2, correctTitle2);
 }
 
 - (void)testControllersChangesMathInModelWhenPickerDidSelectARow
 {
+    
     // Arrange
+    sut.model = [ConverterModel new];
+    sut.model.selectedMathModel = 3;
     
     // Act
+    [sut pickerView:nil didSelectRow:1 inComponent:0];
+    NSUInteger selectedModel = sut.model.selectedMathModel;
     
     // Assert
+    XCTAssertEqual(selectedModel, 1);
 }
 
 - (void)testControllerUpdatesModelWithCorrectTextWhenChangedCharacterInRange
 {
-    // Arrange
-    
-    // Act
-    
-    // Assert
+
 }
 
 
diff --git a/ConverterAppTests/Math/MathBaseTests.m b/ConverterAppTests/Math/MathBaseTests.m
index f69d561..f59287b 100644
--- a/ConverterAppTests/Math/MathBaseTests.m
+++ b/ConverterAppTests/Math/MathBaseTests.m
@@ -20,6 +20,7 @@ @implementation MathBaseTests
 
 - (void)setUp
 {
+
     [super setUp];
     // Put setup code here. This method is called before the invocation of each test method in the class.
 }
@@ -33,10 +34,11 @@ - (void)tearDown
 - (void)testDefaultDirectionSetsToYESOnInit
 {
     // Arrange
-    
+    MathBase *base = [MathBase new];
     // Act
-    
+    BOOL MathBaseDirection = [base defaultDirection];
     // Assert
+    XCTAssertTrue(MathBaseDirection);
 }
 
 @end
diff --git a/ConverterAppTests/Math/MathCelsiusToKTests.m b/ConverterAppTests/Math/MathCelsiusToKTests.m
index 0ccb504..cee5ea6 100644
--- a/ConverterAppTests/Math/MathCelsiusToKTests.m
+++ b/ConverterAppTests/Math/MathCelsiusToKTests.m
@@ -7,6 +7,7 @@
 //
 
 #import <XCTest/XCTest.h>
+#import "MathCelsiusToK.h"
 
 @interface MathCelsiusToKTests : XCTestCase
 
@@ -29,10 +30,23 @@ - (void)tearDown
 - (void)testConvertNumberReturnsCorrectValue
 {
     // Arrange
-    
+    const float accuracy = .1f;
+    MathCelsiusToK *MathCelsiusToKInstance = [MathCelsiusToK new];
     // Act
     
+    // Dictionary with test data, where 'key' is from and 'value' is to.
+    NSDictionary *dataToTest = @{
+                                 [NSNumber numberWithFloat:12.f]:[NSNumber numberWithFloat:285.2f],
+                                 [NSNumber numberWithFloat:362.6f]:[NSNumber numberWithFloat:635.8f],
+                                 [NSNumber numberWithFloat:-31.2f]:[NSNumber numberWithFloat:242.f],
+                                 };
+
     // Assert
+    for(NSNumber *key in dataToTest){
+        NSNumber *from = key;
+        NSNumber *to = [dataToTest objectForKey:key];
+        XCTAssertEqualWithAccuracy([MathCelsiusToKInstance convertNumber:from].floatValue, to.floatValue, accuracy);
+    }
 }
 
 @end
diff --git a/ConverterAppTests/Math/MathInchesToCmTests.m b/ConverterAppTests/Math/MathInchesToCmTests.m
index aad37d5..59fb451 100644
--- a/ConverterAppTests/Math/MathInchesToCmTests.m
+++ b/ConverterAppTests/Math/MathInchesToCmTests.m
@@ -7,6 +7,8 @@
 //
 
 #import <XCTest/XCTest.h>
+#import "MathInchesToCm.h"
+
 
 @interface MathInchesToCmTests : XCTestCase
 
@@ -29,10 +31,24 @@ - (void)tearDown
 - (void)testConvertNumberReturnsCorrectValue
 {
     // Arrange
-    
+    const float accuracy = .1f;
+    MathInchesToCm *MathInchesToCmInstance = [MathInchesToCm new];
     // Act
     
+    // Dictionary with test data, where 'key' is from and 'value' is to.
+    NSDictionary *dataToTest = @{
+                                 [NSNumber numberWithFloat:12.f]:[NSNumber numberWithFloat:30.48f],
+                                 [NSNumber numberWithFloat:.0f]:[NSNumber numberWithFloat:.0f],
+                                 [NSNumber numberWithFloat:44.f]:[NSNumber numberWithFloat:111.8f],
+                                 [NSNumber numberWithFloat:3.6f]:[NSNumber numberWithFloat:9.1f],
+                                 };
+
     // Assert
+    for(NSNumber *key in dataToTest){
+        NSNumber *from = key;
+        NSNumber *to = [dataToTest objectForKey:key];
+        XCTAssertEqualWithAccuracy([MathInchesToCmInstance convertNumber:from].floatValue, to.floatValue, accuracy);
+    }
 }
 
 @end
diff --git a/ConverterAppTests/Math/MathLitersToGalTests.m b/ConverterAppTests/Math/MathLitersToGalTests.m
index 7498a1a..6cf1073 100644
--- a/ConverterAppTests/Math/MathLitersToGalTests.m
+++ b/ConverterAppTests/Math/MathLitersToGalTests.m
@@ -7,6 +7,8 @@
 //
 
 #import <XCTest/XCTest.h>
+#import "MathLitersToGal.h"
+
 
 @interface MathLitersToGalTests : XCTestCase
 
@@ -29,10 +31,24 @@ - (void)tearDown
 - (void)testConvertNumberReturnsCorrectValue
 {
     // Arrange
-    
+    const float accuracy = .1f;
+    MathLitersToGal *MathLitersToGalInstance = [MathLitersToGal new];
     // Act
     
+    // Dictionary with test data, where 'key' is from and 'value' is to.
+    NSDictionary *dataToTest = @{
+                                 [NSNumber numberWithFloat:2.645f]:[NSNumber numberWithFloat:.7f],
+                                 [NSNumber numberWithFloat:.0f]:[NSNumber numberWithFloat:.0f],
+                                 [NSNumber numberWithFloat:.3f]:[NSNumber numberWithFloat:.08f],
+                                 };
+    
     // Assert
+    for(NSNumber *key in dataToTest){
+        NSNumber *from = key;
+        NSNumber *to = [dataToTest objectForKey:key];
+        XCTAssertEqualWithAccuracy([MathLitersToGalInstance convertNumber:from].floatValue, to.floatValue, accuracy);
+    }
+
 }
 
 @end
diff --git a/ConverterAppTests/Math/MathMilesToKmTests.m b/ConverterAppTests/Math/MathMilesToKmTests.m
index b87624c..c7ea039 100644
--- a/ConverterAppTests/Math/MathMilesToKmTests.m
+++ b/ConverterAppTests/Math/MathMilesToKmTests.m
@@ -8,6 +8,7 @@
 
 #import <XCTest/XCTest.h>
 
+#import "MathMilesToKm.h"
 @interface MathMilesToKmTests : XCTestCase
 
 @end
@@ -29,10 +30,24 @@ - (void)tearDown
 - (void)testConvertNumberReturnsCorrectValue
 {
     // Arrange
+    const float accuracy = .1f;
+    MathMilesToKm *MathMilesToKmInstance = [MathMilesToKm new];
     
     // Act
     
+    // Dictionary with test data, where 'key' is from and 'value' is to.
+    NSDictionary *dataToTest = @{
+        [NSNumber numberWithFloat:10.f]:[NSNumber numberWithFloat:16.09f],
+        [NSNumber numberWithFloat:.0f]:[NSNumber numberWithFloat:.0f],
+        [NSNumber numberWithFloat:100.f]:[NSNumber numberWithFloat:160.9f],
+    };
+    
     // Assert
+    for(NSNumber *key in dataToTest){
+        NSNumber *from = key;
+        NSNumber *to = [dataToTest objectForKey:key];
+        XCTAssertEqualWithAccuracy([MathMilesToKmInstance convertNumber:from].floatValue, to.floatValue, accuracy);
+    }
 }
 
 @end