diff --git a/js/common/model/BalanceModel.js b/js/common/model/BalanceModel.js
index 9fd53179..526146c8 100644
--- a/js/common/model/BalanceModel.js
+++ b/js/common/model/BalanceModel.js
@@ -8,7 +8,7 @@
  */
 
 import EnumerationProperty from '../../../../axon/js/EnumerationProperty.js';
-import ObservableArray from '../../../../axon/js/ObservableArray.js';
+import createObservableArray from '../../../../axon/js/createObservableArray.js';
 import Dimension2 from '../../../../dot/js/Dimension2.js';
 import Vector2 from '../../../../dot/js/Vector2.js';
 import inherit from '../../../../phet-core/js/inherit.js';
@@ -32,7 +32,7 @@ function BalanceModel( tandem ) {
 
   // Model elements
   self.fulcrum = new Fulcrum( new Dimension2( 1, FULCRUM_HEIGHT ) );
-  self.massList = new ObservableArray();
+  self.massList = createObservableArray();
   self.userControlledMasses = []; // Masses being controlled by user(s), potentially more than one in touch environment.
 
   self.columnStateProperty = new EnumerationProperty( ColumnState, ColumnState.DOUBLE_COLUMNS, {
diff --git a/js/common/model/Plank.js b/js/common/model/Plank.js
index 1ecfe136..10faf1ed 100644
--- a/js/common/model/Plank.js
+++ b/js/common/model/Plank.js
@@ -8,7 +8,7 @@
 
 import Emitter from '../../../../axon/js/Emitter.js';
 import NumberProperty from '../../../../axon/js/NumberProperty.js';
-import ObservableArray from '../../../../axon/js/ObservableArray.js';
+import createObservableArray from '../../../../axon/js/createObservableArray.js';
 import Property from '../../../../axon/js/Property.js';
 import Matrix3 from '../../../../dot/js/Matrix3.js';
 import Vector2 from '../../../../dot/js/Vector2.js';
@@ -57,9 +57,9 @@ function Plank( position, pivotPoint, columnState, userControlledMasses, tandem
   this.bottomCenterPositionProperty = new Property( position );
 
   // Externally visible observable lists.
-  self.massesOnSurface = new ObservableArray();
-  self.forceVectors = new ObservableArray();
-  self.activeDropPositions = new ObservableArray(); // Positions where user-controlled masses would land if dropped, in meters from center.
+  self.massesOnSurface = createObservableArray();
+  self.forceVectors = createObservableArray();
+  self.activeDropPositions = createObservableArray(); // Positions where user-controlled masses would land if dropped, in meters from center.
 
   // Other external visible attributes.
   self.pivotPoint = pivotPoint;
diff --git a/js/game/model/BalanceGameModel.js b/js/game/model/BalanceGameModel.js
index 3af49465..173cd448 100644
--- a/js/game/model/BalanceGameModel.js
+++ b/js/game/model/BalanceGameModel.js
@@ -10,7 +10,7 @@
  */
 
 import EnumerationProperty from '../../../../axon/js/EnumerationProperty.js';
-import ObservableArray from '../../../../axon/js/ObservableArray.js';
+import createObservableArray from '../../../../axon/js/createObservableArray.js';
 import Property from '../../../../axon/js/Property.js';
 import stepTimer from '../../../../axon/js/stepTimer.js';
 import Dimension2 from '../../../../dot/js/Dimension2.js';
@@ -70,10 +70,10 @@ function BalanceGameModel( tandem ) {
   self.challengeList = null;
 
   // Fixed masses that sit on the plank and that the user must attempt to balance.
-  self.fixedMasses = new ObservableArray();
+  self.fixedMasses = createObservableArray();
 
   // Masses that the user moves on to the plank to counterbalance the fixed masses.
-  self.movableMasses = new ObservableArray();
+  self.movableMasses = createObservableArray();
 
   // Masses that the user is (or users are) moving.
   self.userControlledMasses = [];