Read MainActivity.java

MainActivity
intent -> NumbersActivity, FamilyActivity, ColorsActivity, PhraseActivity

package com.example.android.miwok;

import android.support.v7.app.AppCompactActivity;
import android.os.Bundle;

public class MainActivity extends AppCompactActivity {

	@Override
	protected void onCreate(Bundle savedInstanceState){
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}
}

<application
	android:allowBackup="true"
	android:icon="@mipmap/ic_launcher"
	android:label="Miwok"
	android:supportsRtl="true"
	android:theme="@style/AppTheme" >
	<activity android:name=".MainActivity" >
		<intent-filter>
			<action android:name="android.intent.action.MAIN" />

			<category android:name="android.intent.category.LAUNCHER" />
		</intent-filter>
	</activity>
	<activity android:name=".NumbersActivity" >
	</activity>
	<activity android:name=".FamilyActivity" >
	</activity>
	<activity android:name=".ColorsActivity" >
	</activity>
	<activity android:name=".PhrasesActivity" >
	</activity>
</application>

Navigate to other activities: intent