Update verb usage in sentence (#7070)

src/content/learn/adding-interactivity.md

@@ -265,7 +265,7 @@ setCount(count + 1); // Request a re-render with 1
 console.log(count);  // Still 0!
 ```
 
-This behavior help you avoid subtle bugs. Here is a little chat app. Try to guess what happens if you press "Send" first and *then* change the recipient to Bob. Whose name will appear in the `alert` five seconds later?
+This behavior helps you avoid subtle bugs. Here is a little chat app. Try to guess what happens if you press "Send" first and *then* change the recipient to Bob. Whose name will appear in the `alert` five seconds later?
 
 <Sandpack>