document.write(`

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<h1>Lesson 1 &mdash; Variables, Expressions &amp; Statements</h1>


<h2>Print Statements</h2>
<p><code>print()</code> displays text on the screen. Text must be wrapped in quotes &mdash; single or double both work.</p>
<pre>print("Hello, World!")
print('Python is great')</pre>

<div class="activity">
  <p>Activity 1:</p>
  ` + AB.launchWorld( "9778384549", "Activity 1" ) + `
</div>

<hr>


<h2>Variables</h2>
<p>A variable is a labelled box that stores a value. You give it a name, use <code>=</code> to put something inside, and then refer to that name anywhere in your code.</p>
<pre>name   = 'Alice'
age    = 18
height = 1.65

print(name)
print(age)
print(height)</pre>

<p>There are three data types used above:</p>
<table>
  <tr><th>Type</th><th>Example</th><th>Description</th></tr>
  <tr><td><code>str</code></td><td><code>"Alice"</code></td><td>Text &mdash; always in quotes</td></tr>
  <tr><td><code>int</code></td><td><code>18</code></td><td>Whole number</td></tr>
  <tr><td><code>float</code></td><td><code>1.65</code></td><td>Decimal number</td></tr>
</table>

<div class="activity">
  <p>Activity 2:</p>
  ` + AB.launchWorld( "3674230093", "Activity 2" ) + `
</div>

<hr>


<h2>Rules for Naming Variables</h2>
<table>
  <tr><th>Example</th><th></th><th>Reason</th></tr>
  <tr><td><code>first_name</code></td><td><span class="tick">&#10003; Allowed</span></td><td>Underscores replace spaces</td></tr>
  <tr><td><code>score1</code></td>    <td><span class="tick">&#10003; Allowed</span></td><td>Numbers are fine &mdash; just not at the start</td></tr>
  <tr><td><code>1score</code></td>    <td><span class="cross">&#10007; Not allowed</span></td><td>Cannot start with a number</td></tr>
  <tr><td><code>first name</code></td><td><span class="cross">&#10007; Not allowed</span></td><td>No spaces allowed</td></tr>
  <tr><td><code>class</code></td>     <td><span class="cross">&#10007; Not allowed</span></td><td><code>class</code> is a reserved Python keyword</td></tr>
</table>

<div class="activity">
  <p>Activity 3:</p>
  ` + AB.launchWorld( "3106006044", "Activity 3" ) + `
</div>

<hr>


<h2>Maths and Expressions</h2>
<p>Python supports all standard maths operations. It follows BIMDAS, so brackets are evaluated first.</p>
<table>
  <tr><th>Symbol</th><th>Operation</th><th>Example</th><th>Result</th></tr>
  <tr><td><code>+</code></td> <td>Addition</td>        <td><code>10 + 3</code></td>      <td>13</td></tr>
  <tr><td><code>-</code></td> <td>Subtraction</td>     <td><code>10 - 3</code></td>      <td>7</td></tr>
  <tr><td><code>*</code></td> <td>Multiplication</td>  <td><code>10 * 3</code></td>      <td>30</td></tr>
  <tr><td><code>/</code></td> <td>Division</td>        <td><code>10 / 3</code></td>      <td>3.333&hellip;</td></tr>
  <tr><td><code>//</code></td><td>Floor division</td>  <td><code>10 // 3</code></td>     <td>3 (whole number only)</td></tr>
  <tr><td><code>%</code></td> <td>Modulo</td>          <td><code>10 % 3</code></td>      <td>1 (remainder)</td></tr>
  <tr><td><code>**</code></td><td>Exponentiation</td>  <td><code>10 ** 3</code></td>     <td>1000 (10&sup3;)</td></tr>
</table>
<pre>x = 10
y = 3

print(x + y)        # 13
print(x - y)        # 7
print(x * y)        # 30
print(x / y)        # 3.333...
print(x // y)       # 3
print(x % y)        # 1
print(x ** y)       # 1000
print((2 + 3) * 4)  # 20 -- brackets first</pre>

<div class="activity">
  <p>Activity 4:</p>
  ` + AB.launchWorld( "9765684253", "Activity 4" ) + `
</div>

<hr>


<h2>Getting Input from the User</h2>
<p><code>input()</code> pauses the program and waits for the user to type something. Whatever they type is always returned as a string. We use <code>await</code> because AncientBrain handles input asynchronously.</p>
<pre>user_name = await input("What is your name? ")
print("Nice to meet you,", user_name)</pre>

<p>Because <code>input()</code> always returns text, you must convert it before doing any maths:</p>
<pre>user_age      = await input("How old are you? ")
user_age      = int(user_age)      # convert text to whole number
next_birthday = user_age + 1
print("Next year you will be", next_birthday)</pre>

<table>
  <tr><th>Function</th><th>Converts to</th><th>Example</th></tr>
  <tr><td><code>int()</code></td>  <td>Whole number</td>   <td><code>int("17")</code> &rarr; 17</td></tr>
  <tr><td><code>float()</code></td><td>Decimal number</td> <td><code>float("1.65")</code> &rarr; 1.65</td></tr>
  <tr><td><code>bool()</code></td> <td>True / False</td>   <td><code>bool(1)</code> &rarr; True</td></tr>
</table>

<div class="activity">
  <p>Activity 5:</p>
  ` + AB.launchWorld( "0224952529", "Activity 5" ) + `
</div>

`);