diff --git a/.idea/.name b/.idea/.name
new file mode 100644
index 0000000..d51122f
--- /dev/null
+++ b/.idea/.name
@@ -0,0 +1 @@
+AndroidFundamentalsMai2021
\ No newline at end of file
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 02a3d89..40ca0af 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -11,7 +11,10 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.AndroidFundamentalsMai2021">
-        <activity android:name=".MainActivity">
+        <activity android:name=".ConstraintLayoutSampleActivity"></activity>
+        <activity android:name=".MainActivity" />
+        <activity android:name=".EmailsActivity" />
+        <activity android:name=".StartActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
diff --git a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/ConstraintLayoutSampleActivity.java b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/ConstraintLayoutSampleActivity.java
new file mode 100644
index 0000000..e8c0b7f
--- /dev/null
+++ b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/ConstraintLayoutSampleActivity.java
@@ -0,0 +1,14 @@
+package com.magdamiu.androidfundamentalsmai2021;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.os.Bundle;
+
+public class ConstraintLayoutSampleActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_constraint_layout_sample);
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailAdapter.java b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailAdapter.java
new file mode 100644
index 0000000..4205311
--- /dev/null
+++ b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailAdapter.java
@@ -0,0 +1,40 @@
+package com.magdamiu.androidfundamentalsmai2021;
+
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+
+import java.util.List;
+
+public class EmailAdapter extends RecyclerView.Adapter<EmailViewHolder> {
+    private List<Mail> emails;
+
+    public EmailAdapter(List<Mail> emails) {
+        this.emails = emails;
+    }
+
+    // creates the item view, only the UI elements (it's like a template)
+    @NonNull
+    @Override
+    public EmailViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.email_item, parent, false);
+        return new EmailViewHolder(itemView);
+    }
+
+    // fills the item with the corresponding element from the list (data source)
+    @Override
+    public void onBindViewHolder(@NonNull EmailViewHolder holder, int position) {
+        Mail currentMail = emails.get(position);
+        holder.getTextViewSender().setText(currentMail.getSenderName());
+        holder.getTextViewSubject().setText(currentMail.getSubject());
+    }
+
+    // decides how many items to create in our recycler view
+    @Override
+    public int getItemCount() {
+        return emails.size();
+    }
+}
diff --git a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailViewHolder.java b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailViewHolder.java
new file mode 100644
index 0000000..baa427b
--- /dev/null
+++ b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailViewHolder.java
@@ -0,0 +1,29 @@
+package com.magdamiu.androidfundamentalsmai2021;
+
+import android.view.View;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+
+// the class associated to the item of the recycler view
+// each UI element from the item should have a dedicated field in this class
+public class EmailViewHolder extends RecyclerView.ViewHolder {
+    final private TextView textViewSender;
+    final private TextView textViewSubject;
+
+    public EmailViewHolder(@NonNull View itemView) {
+        super(itemView);
+
+        textViewSender = itemView.findViewById(R.id.textViewSender);
+        textViewSubject = itemView.findViewById(R.id.textViewSubject);
+    }
+
+    public TextView getTextViewSender() {
+        return textViewSender;
+    }
+
+    public TextView getTextViewSubject() {
+        return textViewSubject;
+    }
+}
diff --git a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailsActivity.java b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailsActivity.java
new file mode 100644
index 0000000..74fedcb
--- /dev/null
+++ b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/EmailsActivity.java
@@ -0,0 +1,61 @@
+package com.magdamiu.androidfundamentalsmai2021;
+
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+
+import android.os.Bundle;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class EmailsActivity extends AppCompatActivity {
+
+    private List<Mail> emails;
+    private RecyclerView recyclerViewEmails;
+    private RecyclerView.LayoutManager layoutManager;
+    private EmailAdapter emailAdapter;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_emails);
+
+        // data source for our RecyclerView
+        populateListOfEmails();
+
+        // init the ui elements
+        initView();
+
+        // set the linear layout manager to our recycler view
+        setLayoutManager();
+
+        // set the adapter to our recycler view
+        setAdapter();
+    }
+
+    private void initView() {
+        recyclerViewEmails = findViewById(R.id.recyclerViewEmails);
+    }
+
+    private void populateListOfEmails() {
+        emails = new ArrayList<>();
+        Mail newEmail = new Mail(1, "Magda", "Curs Android");
+        emails.add(newEmail);
+        for (int i = 1; i < 20; i++) {
+            int index = i + 1;
+            newEmail = new Mail(index, "Sender " + index, "Subject " + index);
+            emails.add(newEmail);
+        }
+    }
+
+    private void setLayoutManager() {
+        layoutManager = new LinearLayoutManager(this);
+        recyclerViewEmails.setLayoutManager(layoutManager);
+    }
+
+    private void setAdapter() {
+        emailAdapter = new EmailAdapter(emails);
+        recyclerViewEmails.setAdapter(emailAdapter);
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/Mail.java b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/Mail.java
new file mode 100644
index 0000000..14dc5fc
--- /dev/null
+++ b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/Mail.java
@@ -0,0 +1,37 @@
+package com.magdamiu.androidfundamentalsmai2021;
+
+public class Mail {
+    private int id;
+    private String senderName;
+    private String subject;
+
+    public Mail(int id, String senderName, String subject) {
+        this.id = id;
+        this.senderName = senderName;
+        this.subject = subject;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getSenderName() {
+        return senderName;
+    }
+
+    public void setSenderName(String senderName) {
+        this.senderName = senderName;
+    }
+
+    public String getSubject() {
+        return subject;
+    }
+
+    public void setSubject(String subject) {
+        this.subject = subject;
+    }
+}
diff --git a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/MainActivity.java b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/MainActivity.java
index ab7184b..7c6f37e 100644
--- a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/MainActivity.java
+++ b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/MainActivity.java
@@ -3,7 +3,9 @@
 import androidx.appcompat.app.AppCompatActivity;
 
 import android.os.Bundle;
+import android.text.TextUtils;
 import android.util.Log;
+import android.util.Patterns;
 import android.view.View;
 import android.webkit.WebView;
 import android.widget.AdapterView;
@@ -21,6 +23,8 @@ public class MainActivity extends AppCompatActivity {
     private static final String ANDROID_URL = "https://developer.android.com/";
 
     private EditText editTextName;
+    private EditText editTextEmail;
+    private EditText editTextPhone;
     private Button buttonDisplayGreetings;
     private TextView textViewGreetings;
 
@@ -33,20 +37,22 @@ public class MainActivity extends AppCompatActivity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        /*setContentView(R.layout.activity_main);*/
-        /*setContentView(R.layout.sample);*/
-        // setContentView(R.layout.scrollview_sample);
-        // setContentView(R.layout.webview_sample);
+        /* setContentView(R.layout.activity_main);
+        setContentView(R.layout.sample);
+        setContentView(R.layout.code_challenge_c2);
+        setContentView(R.layout.scrollview_sample);
+        setContentView(R.layout.webview_sample);
         setContentView(R.layout.spinner_sample);
+        setContentView(R.layout.code_challenge2_c3); */
+        setContentView(R.layout.code_challenge1_c3);
 
-        setAndroidVersions();
+        /* setAndroidVersions();
         initialiseSpinnerAdapter();
         setSpinnerAdapter();
-        handlingSpinnerListener();
+        handlingSpinnerListener(); */
 
-        //loadUrl();
-
-        // initViews();
+        // loadUrl();
+        initViews();
         displayLogs();
     }
 
@@ -60,6 +66,7 @@ private void setAndroidVersions() {
         androidVersions.add("kitkat");
     }
 
+
     // step 2: initialise adapter for our spinner
     // ArrayAdapter is a default adapter
     private void initialiseSpinnerAdapter() {
@@ -89,6 +96,7 @@ public void onNothingSelected(AdapterView<?> adapterView) {
         });
     }
 
+
     // webview load url
     private void loadUrl() {
         webView = findViewById(R.id.webViewSample);
@@ -96,11 +104,14 @@ private void loadUrl() {
         webView.loadUrl(ANDROID_URL);
     }
 
+
     // init views for implementing a first simple form
     private void initViews() {
         editTextName = findViewById(R.id.editTextName);
         buttonDisplayGreetings = findViewById(R.id.buttonDisplayGreetings);
         textViewGreetings = findViewById(R.id.textViewGreetings);
+        editTextEmail = findViewById(R.id.editTextEmail);
+        editTextPhone = findViewById(R.id.editTextPhone);
     }
 
     private void displayLogs() {
@@ -128,4 +139,28 @@ public void displayGreetingsOnClick(View view) {
             Toast.makeText(MainActivity.this, getString(R.string.error_insert_name), Toast.LENGTH_LONG).show();
         }
     }
+
+    // Course 3: Code Challenge 1
+    public static boolean isValidEmail(CharSequence target) {
+        return (!TextUtils.isEmpty(target) && Patterns.EMAIL_ADDRESS.matcher(target).matches());
+    }
+
+    public static boolean isValidPhone(CharSequence phone) {
+        return (!TextUtils.isEmpty(phone) && Patterns.PHONE.matcher(phone).matches());
+    }
+
+    public void displaySubmitOnClick(View view) {
+        String inputName = editTextEmail.getText().toString();
+        if (!isValidEmail(inputName)) {
+            editTextEmail.setError(getString(R.string.error_insert_email));
+            Toast.makeText(MainActivity.this, getString(R.string.error_insert_email),
+                    Toast.LENGTH_LONG).show();
+        }
+        inputName = editTextPhone.getText().toString();
+        if (!isValidPhone(inputName)) {
+            editTextPhone.setError(getString(R.string.error_insert_phone));
+            Toast.makeText(MainActivity.this, getString(R.string.error_insert_phone),
+                    Toast.LENGTH_LONG).show();
+        }
+    }
 }
\ No newline at end of file
diff --git a/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/StartActivity.java b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/StartActivity.java
new file mode 100644
index 0000000..a931b73
--- /dev/null
+++ b/app/src/main/java/com/magdamiu/androidfundamentalsmai2021/StartActivity.java
@@ -0,0 +1,34 @@
+package com.magdamiu.androidfundamentalsmai2021;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.View;
+
+public class StartActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_start);
+    }
+
+    public void startMainActivityOnClick(View view) {
+        // starts from the current activity, and moves the user to the Main Activity screen
+        Intent intentToStartMainActivity = new Intent(StartActivity.this, MainActivity.class);
+        startActivity(intentToStartMainActivity);
+    }
+
+    public void startRecyclerViewActivityOnClick(View view) {
+        // starts from the current activity, and moves the user to the Emails Activity screen
+        Intent intentToStartEmailsActivity = new Intent(StartActivity.this, EmailsActivity.class);
+        startActivity(intentToStartEmailsActivity);
+    }
+
+    public void startConstraintActivity(View view) {
+        // starts from the current activity, and moves the user to the Constraint Activity screen
+        Intent intentToStartConstraintActivity = new Intent(StartActivity.this, ConstraintLayoutSampleActivity.class);
+        startActivity(intentToStartConstraintActivity);
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/res/drawable/paint.png b/app/src/main/res/drawable/paint.png
new file mode 100644
index 0000000..a6a6092
Binary files /dev/null and b/app/src/main/res/drawable/paint.png differ
diff --git a/app/src/main/res/layout/activity_constraint_layout_sample.xml b/app/src/main/res/layout/activity_constraint_layout_sample.xml
new file mode 100644
index 0000000..19f0eb0
--- /dev/null
+++ b/app/src/main/res/layout/activity_constraint_layout_sample.xml
@@ -0,0 +1,81 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".ConstraintLayoutSampleActivity">
+
+    <TextView
+        android:id="@+id/textViewTop"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
+        android:layout_marginTop="16dp"
+        android:text="@string/this_is_a_textview_in_a_constraintlayout"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <Button
+        android:id="@+id/button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="56dp"
+        android:text="Button"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.741"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/textViewTop" />
+
+    <TextView
+        android:id="@+id/textView3"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="48dp"
+        android:layout_marginEnd="156dp"
+        android:text="TextView"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/button" />
+
+    <TextView
+        android:id="@+id/textView2"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="8dp"
+        android:layout_marginTop="48dp"
+        android:layout_marginEnd="8dp"
+        android:text="TextView"
+        app:layout_constraintEnd_toStartOf="@+id/textView3"
+        app:layout_constraintHorizontal_bias="0.967"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/button" />
+
+    <androidx.constraintlayout.widget.Group
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        app:constraint_referenced_ids="textView2,textView3" />
+
+    <ImageView
+        android:id="@+id/imageView"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/textView2"
+        tools:srcCompat="@tools:sample/avatars" />
+
+    <TextView
+        android:id="@+id/textView4"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:background="@color/teal_200"
+        android:padding="@dimen/medium_space"
+        android:text="@string/this_is_a_long_text_view_content"
+        app:layout_constraintBottom_toBottomOf="@+id/imageView"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.497"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/imageView" />
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_emails.xml b/app/src/main/res/layout/activity_emails.xml
new file mode 100644
index 0000000..832ed26
--- /dev/null
+++ b/app/src/main/res/layout/activity_emails.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".EmailsActivity">
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/recyclerViewEmails"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_start.xml b/app/src/main/res/layout/activity_start.xml
new file mode 100644
index 0000000..27d81d5
--- /dev/null
+++ b/app/src/main/res/layout/activity_start.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:padding="@dimen/medium_space"
+    tools:context=".StartActivity">
+
+    <Button
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:onClick="startMainActivityOnClick"
+        android:text="@string/start_main_activity" />
+
+    <Button
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:onClick="startRecyclerViewActivityOnClick"
+        android:text="@string/start_recyclerview_activity" />
+
+    <Button
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:onClick="startConstraintActivity"
+        android:text="@string/start_constraint_activity" />
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/code_challenge1_c3.xml b/app/src/main/res/layout/code_challenge1_c3.xml
new file mode 100644
index 0000000..5d1cdab
--- /dev/null
+++ b/app/src/main/res/layout/code_challenge1_c3.xml
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:padding="@dimen/dp_16">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:background="@color/white"
+        android:text="@string/login"
+        android:textColor="@color/orange_FC987E"
+        android:textSize="@dimen/sp_32"
+        android:textStyle="bold" />
+
+    <EditText
+        android:id="@+id/editTextEmail"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:autofillHints="@string/email"
+        android:hint="@string/email"
+        android:inputType="textEmailAddress" />
+
+    <EditText
+        android:id="@+id/editTextPhone"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:autofillHints="@string/phone"
+        android:hint="@string/phone"
+        android:inputType="phone" />
+
+    <CheckBox
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:checked="false"
+        android:text="@string/i_accept_t_amp_c" />
+
+    <Button
+        android:id="@+id/buttonSubmit"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:onClick="displaySubmitOnClick"
+        android:text="@string/submit"
+        android:textColor="@color/white" />
+
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/code_challenge2_c3.xml b/app/src/main/res/layout/code_challenge2_c3.xml
new file mode 100644
index 0000000..042d336
--- /dev/null
+++ b/app/src/main/res/layout/code_challenge2_c3.xml
@@ -0,0 +1,115 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:fillViewport="true">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:padding="@dimen/medium_space">
+
+        <RelativeLayout
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content">
+
+            <View
+                android:layout_width="@dimen/dp_64"
+                android:layout_height="@dimen/dp_64"
+                android:layout_alignParentStart="true"
+                android:background="@color/purple_200" />
+
+            <View
+                android:layout_width="@dimen/dp_64"
+                android:layout_height="@dimen/dp_64"
+                android:layout_alignParentEnd="true"
+                android:background="@color/teal_700" />
+
+            <View
+                android:id="@+id/viewCentre"
+                android:layout_width="@dimen/dp_64"
+                android:layout_height="@dimen/dp_64"
+                android:layout_centerHorizontal="true"
+                android:background="@color/green_A2C89C" />
+
+            <View
+                android:layout_width="@dimen/dp_64"
+                android:layout_height="@dimen/dp_64"
+                android:layout_toEndOf="@id/viewCentre"
+                android:background="@color/orange_FC987E" />
+
+        </RelativeLayout>
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/medium_space"
+            android:text="@string/scroll_view_text" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/medium_space"
+            android:text="@string/scroll_view_text" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/medium_space"
+            android:text="@string/scroll_view_text" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/medium_space"
+            android:text="@string/scroll_view_text" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/medium_space"
+            android:text="@string/scroll_view_text" />
+
+        <FrameLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/dp_64"
+            android:layout_marginBottom="@dimen/dp_64">
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="@dimen/dp_128"
+                android:layout_gravity="center"
+                android:layout_marginStart="@dimen/dp_8"
+                android:layout_marginEnd="@dimen/dp_8"
+                android:background="@color/purple_9B2FAE" />
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="@dimen/dp_64"
+                android:layout_gravity="center"
+                android:layout_marginStart="@dimen/dp_16"
+                android:layout_marginEnd="@dimen/dp_16"
+                android:background="@color/teal_7CCBC5" />
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="@dimen/dp_32"
+                android:layout_gravity="center"
+                android:layout_marginStart="@dimen/dp_24"
+                android:layout_marginEnd="@dimen/dp_24"
+                android:background="@color/yellow_FBC962" />
+
+        </FrameLayout>
+
+        <Spinner
+            android:id="@+id/spinnerAndroidVersions"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/dp_64"
+            android:layout_marginBottom="@dimen/dp_64" />
+
+    </LinearLayout>
+
+</ScrollView>
\ No newline at end of file
diff --git a/app/src/main/res/layout/code_challenge_c2.xml b/app/src/main/res/layout/code_challenge_c2.xml
new file mode 100644
index 0000000..4463d56
--- /dev/null
+++ b/app/src/main/res/layout/code_challenge_c2.xml
@@ -0,0 +1,168 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/dp_150">
+
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:layout_weight="1"
+            android:background="@color/orange_FC987E"
+            android:gravity="center"
+            android:padding="@dimen/dp_17"
+            android:text="@string/this_is_an_orange_textview"
+            android:textAlignment="center"
+            android:textColor="@color/white" />
+
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:layout_weight="1"
+            android:background="@color/green_CDEDD7"
+            android:gravity="center"
+            android:text="@string/this_is_a_green_textview"
+            android:textAlignment="center"
+            android:textColor="@color/black" />
+
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:layout_weight="1"
+            android:background="@color/blue_7BCCC6"
+            android:gravity="center"
+            android:text="@string/this_is_a_blue_textview"
+            android:textAlignment="center"
+            android:textColor="@color/white" />
+    </LinearLayout>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/dp_150">
+
+        <Button
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:layout_margin="@dimen/dp_5"
+            android:layout_weight="1"
+            android:backgroundTint="@color/blue_7BCCC6"
+            android:text="@string/this_is_a_button"
+            android:textColor="@color/black" />
+
+        <ImageView
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:layout_weight="1"
+            android:scaleType="fitCenter"
+            android:contentDescription="@string/paint_image"
+            android:src="@drawable/paint" />
+
+        <Button
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:layout_margin="@dimen/dp_5"
+            android:layout_weight="1"
+            android:backgroundTint="@color/green_A2C89C"
+            android:gravity="center"
+            android:text="@string/this_is_a_green_button"
+            android:textColor="@color/black" />
+    </LinearLayout>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/dp_120"
+        android:background="@color/yellow_FBC962"
+        android:orientation="vertical"
+        android:paddingTop="@dimen/dp_20"
+        android:paddingBottom="@dimen/dp_20">
+
+        <EditText
+            android:layout_width="match_parent"
+            android:layout_height="@dimen/dp_0"
+            android:layout_weight="1"
+            android:autofillHints="@string/edit_this"
+            android:hint="@string/this_is_an_edittext"
+            android:inputType="textCapWords"
+            android:textColor="@color/purple_700" />
+
+        <EditText
+            android:layout_width="match_parent"
+            android:layout_height="@dimen/dp_0"
+            android:layout_weight="1"
+            android:autofillHints="@string/edit_this"
+            android:hint="@string/this_is_a_new_edittext"
+            android:inputType="textCapWords"
+            android:textColor="@color/purple_700" />
+
+    </LinearLayout>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:background="@color/blue_7BCCC6"
+        android:orientation="vertical">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="@dimen/dp_50">
+
+            <CheckBox
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:layout_marginStart="@dimen/dp_10"
+                android:layout_weight="1"
+                android:checked="false"
+                android:text="@string/notify_me"
+                android:textSize="@dimen/sp_20" />
+
+            <androidx.appcompat.widget.SwitchCompat
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:layout_weight="1"
+                android:text="@string/auto_backup"
+                android:textSize="@dimen/sp_16" />
+        </LinearLayout>
+
+        <View
+            android:layout_width="match_parent"
+            android:layout_height="@dimen/dp_2"
+            android:background="@color/purple_200" />
+
+        <RatingBar
+            style="@style/Widget.AppCompat.RatingBar.Small"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/dp_15"
+            android:layout_marginBottom="@dimen/dp_15"
+            android:isIndicator="false"
+            android:numStars="5"
+            android:progressTint="@color/pink_FC4481"
+            android:rating="4" />
+
+        <View
+            android:layout_width="match_parent"
+            android:layout_height="@dimen/dp_2"
+            android:background="@color/purple_200" />
+
+        <RadioGroup
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content">
+
+            <RadioButton
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="@string/yes" />
+
+            <RadioButton
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="@string/no" />
+        </RadioGroup>
+
+    </LinearLayout>
+
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/email_item.xml b/app/src/main/res/layout/email_item.xml
new file mode 100644
index 0000000..779702e
--- /dev/null
+++ b/app/src/main/res/layout/email_item.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical"
+    android:padding="@dimen/medium_space">
+
+    <TextView
+        android:id="@+id/textViewSender"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content" />
+
+    <TextView
+        android:id="@+id/textViewSubject"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="@dimen/medium_space" />
+
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/colors.xml b/app/src/main/res/values/colors.xml
index d8ce349..1c3127d 100644
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -8,4 +8,12 @@
     <color name="black">#FF000000</color>
     <color name="white">#FFFFFFFF</color>
     <color name="red">#ff3412</color>
+    <color name="orange_FC987E">#FC987E</color>
+    <color name="green_CDEDD7">#CDEDD7</color>
+    <color name="blue_7BCCC6">#7BCCC6</color>
+    <color name="green_A2C89C">#A2C89C</color>
+    <color name="yellow_FBC962">#FBC962</color>
+    <color name="pink_FC4481">#FC4481</color>
+    <color name="purple_9B2FAE">#9B2FAE</color>
+    <color name="teal_7CCBC5">#7CCBC5</color>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/dimens.xml b/app/src/main/res/values/dimens.xml
index e8b2c28..7e0a65a 100644
--- a/app/src/main/res/values/dimens.xml
+++ b/app/src/main/res/values/dimens.xml
@@ -2,6 +2,25 @@
 <resources>
     <dimen name="medium_text">23sp</dimen>
     <dimen name="medium_space">16dp</dimen>
+    <dimen name="dp_5">5dp</dimen>
+    <dimen name="dp_150">150dp</dimen>
+    <dimen name="dp_17">17dp</dimen>
+    <dimen name="dp_120">120dp</dimen>
+    <dimen name="dp_0">0dp</dimen>
+    <dimen name="dp_50">50dp</dimen>
+    <dimen name="dp_10">10dp</dimen>
+    <dimen name="sp_20">20sp</dimen>
+    <dimen name="sp_16">16sp</dimen>
+    <dimen name="dp_2">2dp</dimen>
+    <dimen name="dp_15">15dp</dimen>
+    <dimen name="dp_20">20dp</dimen>
+    <dimen name="dp_128">128dp</dimen>
+    <dimen name="dp_64">64dp</dimen>
+    <dimen name="dp_8">8dp</dimen>
+    <dimen name="dp_16">16dp</dimen>
+    <dimen name="dp_24">24dp</dimen>
+    <dimen name="dp_32">32dp</dimen>
+    <dimen name="sp_32">32sp</dimen>
     <dimen name="space_128">128dp</dimen>
     <dimen name="space_64">64dp</dimen>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 0f8b9c3..533d498 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -12,10 +12,36 @@
     <string name="please_add_your_name_here">Please add your name here</string>
     <string name="greetings">Greetings :)</string>
     <string name="error_insert_name">Please insert a name</string>
+    <string name="error_insert_email">Fill the input with a valid email address</string>
+    <string name="error_insert_phone">Fill the input with a valid phone number</string>
+    <string name="this_is_an_orange_textview">This is an orange TextView</string>
+    <string name="this_is_a_green_textview">This is a green TextView</string>
+    <string name="this_is_a_blue_textview">This is a blue TextView</string>
+    <string name="this_is_a_button">this is a button</string>
+    <string name="this_is_an_edittext">This is an EditText</string>
+    <string name="this_is_a_new_edittext">This is a new EditText</string>
+    <string name="notify_me">Notify me :)</string>
+    <string name="auto_backup">Auto backup</string>
+    <string name="this_is_a_green_button">This is a green button</string>
+    <string name="edit_this">edit this...</string>
+    <string name="paint_image">paint image</string>
+    <string name="text_on_the_left">text on the left</string>
+    <string name="scroll_view_text">ScrollView: A view group that allows the view hierarchy placed within it to be scrolled. Scroll view may have only one direct child placed within it. To add multiple views within the scroll view, make the direct child you add a view group, for example LinearLayout, and place additional views within that LinearLayout.</string>
+    <string name="login">LOGIN</string>
+    <string name="email">Email</string>
+    <string name="phone">Phone</string>
+    <string name="i_accept_t_amp_c"><![CDATA[I accept T&C]]></string>
+    <string name="submit">SUBMIT</string>
     <string name="textview_3">TextView 3</string>
     <string name="textview_2">TextView 2</string>
     <string name="textview_1">TextView 1</string>
     <string name="long_text">Of course, you’d want to replace the URL after git remote add upstream with the appropriate clone URL for the original project repository. For the rest of this article, I’m going to assume you used upstream as the name for this additional Git remote. Now, you could try pushing changes to the original repository using git push at this point, but it would probably fail because you probably don’t have permission to push changes directly to the repository. Besides, it really wouldn’t be a good idea. That’s because other people might be working on the project as well, and how in the world would we keep track of everyone’s changes? That’s where branches come in.</string>
     <string name="text_on_the_right">text on the right</string>
     <string name="text_centered_in_parent">text centered in parent</string>
+    <string name="start_mainactivity">Start MainActivity</string>
+    <string name="start_recyclerview_activity">START RECYCLERVIEW ACTIVITY</string>
+    <string name="start_main_activity">START MAIN ACTIVITY</string>
+    <string name="start_constraint_activity">START CONSTRAINT ACTIVITY</string>
+    <string name="this_is_a_textview_in_a_constraintlayout">This is a TextView in a ConstraintLayout</string>
+    <string name="this_is_a_long_text_view_content">this is a long text view content</string>
 </resources>
\ No newline at end of file