typo

lectures/concurrency/index.html

@@ -346,7 +346,7 @@ <h2>Mutexes and <code>synchronized</code></h2>
 <p>
 A <b>lock</b> is a special object that can be <b>held</b> by threads, with some
 restriction on which threads can hold it. The simplest form of lock is a
-<b>mutual exclusion locks</b>, or <b>mutex</b>, which can be held by at
+<b>mutual exclusion lock</b>, or <b>mutex</b>, which can be held by at
 most one thread at a time.
 </p>
 <p>

lectures/guievents/index.html

@@ -264,7 +264,9 @@ <h2>Animation</h2>
 by interpolating the values of properties between key frames. For example,
 the following figure shows how the position of an object on the screen might
 be controlled by a sequence of key frames that specify its horizontal and
-vertical position.
+vertical position. Of course, properties other than position can also be
+controlled in this way, including properties like rotational orientation
+or even color.
 </p>
 <div class=figure>
 <canvas id="keyframe_animation" style="height: 400px">

lectures/uidesign/index.html

@@ -178,9 +178,9 @@ <h2>UI as dialogue</h2>
         <li> &lt;1/30: fast enough for continuous-feedback tasks (e.g., mouse tracking)
         <li> &lt;1/10s: imperceptible delay for discrete actions, e.g. button clicks.
         <li> &lt;1/2s: fast but noticeable (ok for command-response interaction)
-        <li> 1/2s-5s: increasingly annoying but user stays focused
-        <li> 5s-10s: User starts to lose attention.
-        <li> 10s-1 min$: User becomes distracted and
+        <li> 1/2s–5s: increasingly annoying but user stays focused
+        <li> 5s–10s: User starts to lose attention.
+        <li> 10s–1 min$: User becomes distracted and
         productivity declines. App needs to support parallel activities.
         <li> &gt;1 min: Significant loss of productivity.  User leaves for coffee.
         </ul>