Fixed typo: added 'are' (#4026)

content/tutorial/tutorial.md

@@ -1045,7 +1045,7 @@ Let's `map` over the `history` in the Game's `render` method:
 
 **[View the full code at this point](https://codepen.io/gaearon/pen/EmmGEa?editors=0010)**
 
-As we iterate through `history` array, `step` variable refers to the current `history` element value, and `move` refers to the current `history` element index. We only interested in `move` here, hence `step` is not getting assigned to anything.
+As we iterate through `history` array, `step` variable refers to the current `history` element value, and `move` refers to the current `history` element index. We are only interested in `move` here, hence `step` is not getting assigned to anything.
 
 For each move in the tic-tac-toe game's history, we create a list item `<li>` which contains a button `<button>`. The button has a `onClick` handler which calls a method called `this.jumpTo()`. We haven't implemented the `jumpTo()` method yet. For now, we should see a list of the moves that have occurred in the game and a warning in the developer tools console that says: