diff --git a/src/activities/alphabet-sequence/AlphabetSequence.qml b/src/activities/alphabet-sequence/AlphabetSequence.qml
--- a/src/activities/alphabet-sequence/AlphabetSequence.qml
+++ b/src/activities/alphabet-sequence/AlphabetSequence.qml
@@ -28,6 +28,7 @@
     // Supports multigraphs, e.g. /sh/ or /sch/ gets treated as one letter
     property string alphabet: qsTr("a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z");
 
+    showTutorial: false
     dataset: [
         {
             data: activity.alphabet.split("/"),
diff --git a/src/activities/numbers-odd-even/resource/1/Data.qml b/src/activities/numbers-odd-even/resource/1/Data.qml
--- a/src/activities/numbers-odd-even/resource/1/Data.qml
+++ b/src/activities/numbers-odd-even/resource/1/Data.qml
@@ -25,7 +25,7 @@
 Dataset {
     objective: qsTr("Select even and odd numbers up to 20")
     difficulty: 1
-    //: If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
+    // If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
     data: [
         {
             data: "0 2 4".split(" "),
diff --git a/src/activities/numbers-odd-even/resource/2/Data.qml b/src/activities/numbers-odd-even/resource/2/Data.qml
--- a/src/activities/numbers-odd-even/resource/2/Data.qml
+++ b/src/activities/numbers-odd-even/resource/2/Data.qml
@@ -25,7 +25,7 @@
 Dataset {
     objective: qsTr("Select even and odd numbers up to 30")
     difficulty: 1
-    //: If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
+    // If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
     data: [
         {
             data: "0 2 4 6 8 10 12 14 16 18 20".split(" "),
diff --git a/src/activities/planegame/Planegame.qml b/src/activities/planegame/Planegame.qml
--- a/src/activities/planegame/Planegame.qml
+++ b/src/activities/planegame/Planegame.qml
@@ -82,7 +82,7 @@
             property alias movePlaneTimer: movePlaneTimer
             property alias cloudCreation: cloudCreation
             property bool showTutorial: activity.showTutorial
-            property var letterMode: activity.mode
+            property string letterMode: activity.mode
        }
 
         onStart: { Activity.start(items, dataset) }
diff --git a/src/activities/planegame/planegame.js b/src/activities/planegame/planegame.js
--- a/src/activities/planegame/planegame.js
+++ b/src/activities/planegame/planegame.js
@@ -78,7 +78,7 @@
 }
 
 function initLevel() {
-    items.bar.level = currentLevel + 1;
+    items.bar.level = currentLevel + 1
     currentSubLevel = 0
     numberOfSubLevels = dataset[currentLevel].data.length
     if(items.letterMode === "upper") {
diff --git a/src/activities/planegame/resource/1/Data.qml b/src/activities/planegame/resource/1/Data.qml
--- a/src/activities/planegame/resource/1/Data.qml
+++ b/src/activities/planegame/resource/1/Data.qml
@@ -25,7 +25,7 @@
 Dataset {
     objective: qsTr("Count numbers up to 15")
     difficulty: 1
-    //: If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
+    // If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
     data: [
         {
             data: "0 1 2 3".split(" "),
diff --git a/src/activities/planegame/resource/2/Data.qml b/src/activities/planegame/resource/2/Data.qml
--- a/src/activities/planegame/resource/2/Data.qml
+++ b/src/activities/planegame/resource/2/Data.qml
@@ -25,7 +25,7 @@
 Dataset {
     objective: qsTr("Count numbers up to 20")
     difficulty: 2
-    //: If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
+    // If the value of variable showNext is true then the next number to be selected is shown as hint, otherwise not.
     data: [
         {
             data: "0 1 2 3 4 5 6 7 8 9 10".split(" "),