typo fix

Author: gaearon

beta/src/pages/learn/you-might-not-need-an-effect.md

@@ -1571,7 +1571,7 @@ label, textarea { margin-bottom: 10px; display: block; }
 
 <Solution>
 
-The `isSent` state variable determines whether to show the form or the "Thank you" dialog. However, you aren't sending the message because the "Thank you" dialog was _displayed_. You want to send the message because the user has _submitted the form._ Delete the misleading Effect and move the `sendMessage` call inside the `handleSubmit` event handler:
+The `showForm` state variable determines whether to show the form or the "Thank you" dialog. However, you aren't sending the message because the "Thank you" dialog was _displayed_. You want to send the message because the user has _submitted the form._ Delete the misleading Effect and move the `sendMessage` call inside the `handleSubmit` event handler:
 
 <Sandpack>