diff --git a/js/density-main.ts b/js/density-main.ts
index 4a423b1..78694be 100644
--- a/js/density-main.ts
+++ b/js/density-main.ts
@@ -19,6 +19,7 @@ import DensityDescriptionStrings_en from './description/density-description-stri
 import DensityDescriptionStrings_es from './description/density-description-strings_es.js'; // eslint-disable-line default-import-match-filename
 import DensityDescriptionLogic from './description/density-description-logic.js'; // eslint-disable-line default-import-match-filename
 import DescriptionContext from '../../joist/js/DescriptionContext.js';
+import '../../scenery-phet/js/accessibility/describers/Alerter.js';
 
 const simOptions: SimOptions = {
   credits: {
diff --git a/js/description/density-description-logic.js b/js/description/density-description-logic.js
index 1e78766..09f9403 100644
--- a/js/description/density-description-logic.js
+++ b/js/description/density-description-logic.js
@@ -12,6 +12,30 @@ export default () => phet.joist.DescriptionContext.registerLogic( {
     if ( introScreen ) {
       const introScreenView = context.get( 'density.introScreen.view' );
 
+      const alerter = new phet.sceneryPhet.Alerter( {
+        alertToVoicing: false,
+        descriptionAlertNode: introScreenView
+      } );
+
+      const blockA = context.get( 'density.introScreen.model.blocks.blockA' );
+      const blockB = context.get( 'density.introScreen.model.blocks.blockB' );
+
+      [ blockA, blockB ].forEach( block => {
+        const isBlockA = block === blockA;
+
+        // const blockUtterance = new phet.utteranceQueue.Utterance( {
+        //
+        // } );
+
+        context.lazyLink( block.visibleProperty, isVisible => {
+          alerter.alert( strings.blockVisibilityAlert( isBlockA, isVisible ) );
+        } );
+        context.lazyLink( block.userControlledProperty, userControlled => {
+          alerter.alert( strings.blockUserControlledAlert( isBlockA, userControlled ) );
+        } );
+      } );
+
+
       const simStateDescriptionNode = new phet.scenery.Node( {
         tagName: 'p'
       } );
@@ -30,11 +54,13 @@ export default () => phet.joist.DescriptionContext.registerLogic( {
         ]
       } ) );
 
-      const modeProperty = context.get( 'density.introScreen.model.modeProperty' );
-
-      context.link( modeProperty, mode => {
+      context.link( context.get( 'density.introScreen.model.modeProperty' ), mode => {
         simStateDescriptionNode.innerContent = strings.screenSummarySimStateDescription( mode.toString() );
       } );
+
+      // context.lazyLink( context.get( 'density.introScreen.model.modeProperty' ), mode => {
+      //   alerter.alert( mode.toString() === 'ONE_BLOCK' ? strings.oneBlockAlert() : strings.twoBlockAlert() );
+      // } );
     }
   },
   added( tandemID, obj ) {
diff --git a/js/description/density-description-strings_en.js b/js/description/density-description-strings_en.js
index 616a34e..eeb7a27 100644
--- a/js/description/density-description-strings_en.js
+++ b/js/description/density-description-strings_en.js
@@ -11,14 +11,12 @@ export default () => phet.joist.DescriptionContext.registerStrings( {
   screenSummarySimStateDescription(
     blockMode
   ) {
-    if ( blockMode.toString() === 'ONE_BLOCK' ) {
-      return 'We have one block';
-    }
-    else if ( blockMode.toString() === 'TWO_BLOCKS' ) {
-      return 'We have two blocks';
-    }
-    else {
-      throw new Error();
-    }
+    return `There ${blockMode === 'ONE_BLOCK' ? 'is one block' : 'are two blocks'}.`;
+  },
+  blockVisibilityAlert( isBlockA, isVisible ) {
+    return `Block ${isBlockA ? 'A' : 'B'} ${isVisible ? 'added' : 'removed'}`;
+  },
+  blockUserControlledAlert( isBlockA, isUserControlled ) {
+    return `${isUserControlled ? 'Grabbed' : 'Dropped'} block ${isBlockA ? 'A' : 'B'}`;
   }
 } );