Fixed minor typos and added an explanation about the logical NOT oper…

…ator.

index.html

@@ -16,7 +16,7 @@ <h1>Curriculum: second day</h1>
 
 <p>Today, our goal is to learn how JavaScript can create and edit the
 content and appearance of a web page. When we use our awesome
-Javascript power to change the content or its appearance, we can make
+JavaScript power to change the content or its appearance, we can make
 text, shapes and pictures appear, disappear and move around. The
 content is HTML, and the appearance is described in CSS.</p>
 

page1.html

@@ -76,7 +76,7 @@ <h3 class=inst>Instructions</h3>
 
 <h3 class=ex>Explanation</h3>
 
-<p>No where in this HTML page have we said how big to make the
+<p>Nowhere in this HTML page have we said how big to make the
 heading, that text in <code>&lt;strong></code> tags should be bold,
 that <code>&lt;em></code> should be italic, that there should be space
 above and below <code>&lt;p></code> tags.</p>
@@ -155,7 +155,7 @@ <h3 class=ex>Explanation</h3>
 <h2>More JavaScript please!</h2>
 
 <p>There is a lot to learn about both HTML and CSS, but hopefully
-that’s enough of an introduction will help us so we add our magic
+that’s enough of an introduction to help us as we add our magic
 power: JavaScript!</p>
 
 

page3.html

@@ -393,9 +393,17 @@ <h3 class=ex>Explanation</h3>
 
 <p>We created a variable that remembers whether or not we are already
 scrolling, and if we are, we ignore the keydown event from the
-user. Maybe this is not what the user expects. What is reasonable for
-the user to expect? How can we change the code to do what the user
-expects?</p>
+user.</p>
+
+<p>You will notice that this solution uses an exclamation mark in the
+<code>if (!scrolling)</code> conditional statement (inside the
+<code>handleEvent</code> function). The exclamation mark is called the logical
+NOT operator in JavaScript, so the <code>if (!scrolling)</code>
+conditional statement has the meaning "if the scrolling variable is not true".</p>
+
+<p>Maybe this solution to the problem does not fit with what the user expects. What is
+reasonable for the user to expect? How can we change the code to do what the
+user expects?</p>
 
 
 <h2>Next!</h2>