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<!DOCTYPE html>
<html lang="en">
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  <title>Chapter 06 — Suburban Scene</title>
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      <div class="ch-label">Chapter 6 of 6</div>
      <h1>Suburban Scene</h1>
      <p class="lead">Bring everything together — use functions, loops, and conditionals to build a complete neighbourhood from geometric components.</p>
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        <h1>A Square</h1>
        <p class="lead">You have been drawing squares since Chapter 1. This final chapter brings every skill together to build a whole neighbourhood from reusable components. Let's start by recapping the foundation — a function that draws a square of any size.</p>
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          <pre><span class="kw">func</span> <span class="fn">drawSquare</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="kw">for</span> _ <span class="kw">in</span> <span class="num">1</span>...<span class="num">4</span> {
        pen.<span class="fn">move</span>(size)
        pen.<span class="fn">turn</span>(<span class="num">90</span>)
    }
}</pre>
        </div>

        <p>Notice that the pen is passed <em>as a parameter</em>. This is an important design pattern — it means <code>drawSquare</code> can work with any pen, in any colour, wherever the pen happens to be positioned. All the functions you write in this chapter should follow the same pattern.</p>

        <p>You will also need to <strong>reposition the pen</strong> between components without drawing a line. Use <code>penUp()</code> and <code>penDown()</code> for this:</p>

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          <pre><span class="cm">// Lift the pen, travel, lower it again</span>
pen.<span class="fn">penUp</span>()
pen.<span class="fn">move</span>(<span class="num">50</span>)   <span class="cm">// no line is drawn</span>
pen.<span class="fn">penDown</span>()
pen.<span class="fn">move</span>(<span class="num">50</span>)   <span class="cm">// drawing resumes</span></pre>
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        <p>It is worth writing a small <strong>jump helper</strong> that you can use throughout this chapter:</p>

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          <pre><span class="kw">func</span> <span class="fn">jump</span>(pen: <span class="tp">Pen</span>, distance: <span class="tp">Double</span>) {
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">move</span>(distance)
    pen.<span class="fn">penDown</span>()
}</pre>
        </div>

        <p>With these two building blocks — a drawing function and a movement helper — you are ready to assemble a neighbourhood.</p>

        <div class="img-placeholder">
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          <span class="img-name">06-01-a-square.png</span>
          <span class="img-hint">Image coming soon</span>
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        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Geometry — Properties of Shapes</td><td>A square has four equal sides and four right angles (90° turns). Encoding these constraints in a function ensures every drawn square satisfies both conditions automatically.</td></tr>
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         SECTION 02 — A Triangle
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    <section id="s02">
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        <span class="section-tag exercise">◆ Exercise</span>
        <h1>A Triangle</h1>
        <p class="lead">Every building in our scene needs a roof. Write a function <code>drawRoof(pen:base:)</code> that draws an <strong>equilateral triangle</strong> — this gives a clean, symmetric roof shape.</p>
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        <p>Remember from Chapter 3: for an equilateral triangle (three equal sides, three 60° angles), the pen needs to turn by the <strong>exterior angle</strong> at each vertex. What is the exterior angle of an equilateral triangle?</p>

        <div class="callout">
          <strong>Hint:</strong> The sum of exterior angles of any polygon is 360°. For an equilateral triangle, all three exterior angles are equal.
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          <pre><span class="cm">// Draw an equilateral triangle roof.
// The pen starts at the bottom-left corner, facing right.
// After the call, the pen is at the bottom-right corner, facing right.
// (The base itself is NOT drawn — it is the top edge of the wall below.)</span>
<span class="kw">func</span> <span class="fn">drawRoof</span>(pen: <span class="tp">Pen</span>, base: <span class="tp">Double</span>) {
    <span class="cm">// your code here</span>
}</pre>
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            <pre><span class="cm">// An equilateral triangle has exterior angles of 360° ÷ 3 = 120°.
// The pen turns left 60° to head up the left slope, reaches the apex,
// then turns right 120° to head down the right slope.</span>
<span class="kw">func</span> <span class="fn">drawRoof</span>(pen: <span class="tp">Pen</span>, base: <span class="tp">Double</span>) {
    pen.<span class="fn">turn</span>(-<span class="num">60</span>)   <span class="cm">// face upper-right at 60° above horizontal</span>
    pen.<span class="fn">move</span>(base)   <span class="cm">// go to apex</span>
    pen.<span class="fn">turn</span>(<span class="num">120</span>)    <span class="cm">// turn to face lower-right at 60° below horizontal</span>
    pen.<span class="fn">move</span>(base)   <span class="cm">// go to bottom-right corner</span>
    pen.<span class="fn">turn</span>(-<span class="num">60</span>)   <span class="cm">// back to original heading (facing right)</span>
}

<span class="cm">// Test it</span>
<span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
pen.<span class="vr">color</span> = .<span class="vr">red</span>
<span class="fn">drawRoof</span>(pen: pen, base: <span class="num">100</span>)</pre>
          </div>
          <p>The three turns sum to −60° + 120° + (−60°) = 0°, which means the pen ends up facing the same direction it started — a useful property when composing shapes.</p>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-02-a-triangle.png</span>
          <span class="img-hint">Image coming soon</span>
        </div>

        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Geometry — Triangles</td><td>Exterior angle theorem: the exterior angle at each vertex equals the supplement of the interior angle. For an equilateral triangle, each interior angle = 60°, so each exterior angle = 120°. The total of all exterior angles = 360°.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 03 — A Cross
    ════════════════════════════════════════ -->
    <section id="s03">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>A Cross</h1>
        <p class="lead">Churches need a cross! Write <code>drawCross(pen:size:)</code> that draws a plus-sign cross as two perpendicular strokes of equal length. Use <code>penUp()</code> and <code>penDown()</code> to lift the pen between strokes so no unwanted lines appear.</p>
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      <div class="article">
        <p>The cross should be symmetric: each arm extends <code>size / 2</code> from the centre point.</p>

        <div class="code-wrap">
          <div class="code-header">
            <span class="code-lang">Swift</span>
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          </div>
          <pre><span class="cm">// Draw a plus-sign cross.
// The pen starts at the BOTTOM of the vertical stroke, facing right.
// After the call it returns to the same position and heading.</span>
<span class="kw">func</span> <span class="fn">drawCross</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="kw">let</span> <span class="vr">half</span> = size / <span class="num">2</span>
    <span class="cm">// Step 1: draw the vertical stroke (up through the centre to the top)</span>
    <span class="cm">// Step 2: penUp back to the centre, then left to the start of the horizontal stroke</span>
    <span class="cm">// Step 3: draw the horizontal stroke</span>
    <span class="cm">// Step 4: return pen to original position and heading</span>
    <span class="cm">// your code here</span>
}</pre>
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            <pre><span class="kw">func</span> <span class="fn">drawCross</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="kw">let</span> <span class="vr">half</span> = size / <span class="num">2</span>

    <span class="cm">// ── Vertical stroke ──────────────────────────────────</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)        <span class="cm">// face upward</span>
    pen.<span class="fn">move</span>(size)        <span class="cm">// draw from bottom to top</span>

    <span class="cm">// Lift pen, go back to centre</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(<span class="num">180</span>)         <span class="cm">// face downward</span>
    pen.<span class="fn">move</span>(half)        <span class="cm">// back to centre, no drawing</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)        <span class="cm">// face left</span>
    pen.<span class="fn">move</span>(half)        <span class="cm">// go to left end of horizontal arm</span>
    pen.<span class="fn">turn</span>(<span class="num">180</span>)         <span class="cm">// face right</span>
    pen.<span class="fn">penDown</span>()

    <span class="cm">// ── Horizontal stroke ─────────────────────────────────</span>
    pen.<span class="fn">move</span>(size)         <span class="cm">// draw from left end to right end</span>

    <span class="cm">// ── Return to start position, facing right ────────────</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(<span class="num">180</span>)          <span class="cm">// face left</span>
    pen.<span class="fn">move</span>(half)         <span class="cm">// back to centre</span>
    pen.<span class="fn">turn</span>(<span class="num">90</span>)           <span class="cm">// face down</span>
    pen.<span class="fn">move</span>(half)         <span class="cm">// back to bottom</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)         <span class="cm">// face right (original heading)</span>
    pen.<span class="fn">penDown</span>()
}

<span class="cm">// Test it</span>
<span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
pen.<span class="vr">color</span> = .<span class="vr">white</span>
<span class="fn">drawCross</span>(pen: pen, size: <span class="num">40</span>)</pre>
          </div>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-03-a-cross.png</span>
          <span class="img-hint">Image coming soon</span>
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        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Geometry — Perpendicular Lines</td><td>The two strokes of the cross are perpendicular (intersecting at 90°). Using <code>turn(-90)</code> and <code>turn(90)</code> encodes perpendicularity directly in the code.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 04 — A Church
    ════════════════════════════════════════ -->
    <section id="s04">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>A Church</h1>
        <p class="lead">Now compose your three building-block functions into a complete church. Write <code>drawChurch(pen:size:)</code> that draws:</p>
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      <div class="article">
        <ul>
          <li>A square <strong>body</strong> (colour: <code>.gray</code>)</li>
          <li>A triangular <strong>roof</strong> sitting on top (colour: <code>.red</code>)</li>
          <li>A small <strong>cross</strong> at the apex of the roof (colour: <code>.white</code>)</li>
        </ul>

        <p>This is the key skill of Chapter 6: carefully <strong>repositioning</strong> the pen between each component using <code>penUp()</code> and <code>penDown()</code>.</p>

        <div class="callout">
          <strong>Tip:</strong> After <code>drawSquare</code> the pen is back at its starting position, facing right. To reach the top-left corner of the square, turn left and move <code>size</code> upward. After <code>drawRoof</code> the pen is at the top-right corner of the roof base, facing right.
        </div>

        <div class="code-wrap">
          <div class="code-header">
            <span class="code-lang">Swift</span>
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          <pre><span class="kw">func</span> <span class="fn">drawChurch</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="cm">// 1. Draw the body</span>
    pen.<span class="vr">color</span> = .<span class="vr">gray</span>
    <span class="fn">drawSquare</span>(pen: pen, size: size)

    <span class="cm">// 2. Move to top-left corner of body, then draw roof</span>
    <span class="cm">// your code here</span>

    <span class="cm">// 3. Move to the apex of the roof, then draw cross</span>
    <span class="cm">// your code here</span>
}</pre>
        </div>

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            <pre><span class="kw">func</span> <span class="fn">drawChurch</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="cm">// ── 1. Body ──────────────────────────────────────────</span>
    pen.<span class="vr">color</span> = .<span class="vr">gray</span>
    <span class="fn">drawSquare</span>(pen: pen, size: size)
    <span class="cm">// Pen is back at bottom-left, facing right.</span>

    <span class="cm">// ── 2. Roof ───────────────────────────────────────────</span>
    <span class="cm">// Move to top-left corner (turn up, walk size, turn right)</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)         <span class="cm">// face up</span>
    pen.<span class="fn">move</span>(size)         <span class="cm">// arrive at top-left of body</span>
    pen.<span class="fn">turn</span>(<span class="num">90</span>)           <span class="cm">// face right</span>
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">red</span>
    <span class="fn">drawRoof</span>(pen: pen, base: size)
    <span class="cm">// Pen is now at top-right of roof base, facing right.</span>

    <span class="cm">// ── 3. Cross at the apex ──────────────────────────────</span>
    <span class="cm">// Apex is at base/2 to the left and base*sin(60°) ≈ base*0.87 up.</span>
    <span class="cm">// Simpler: move left to centre of roof base, then up to apex height.</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(<span class="num">180</span>)          <span class="cm">// face left</span>
    pen.<span class="fn">move</span>(size / <span class="num">2</span>)    <span class="cm">// reach horizontal centre</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)         <span class="cm">// face up</span>
    pen.<span class="fn">move</span>(size * <span class="num">0.87</span>) <span class="cm">// move up approx to apex (sin 60° ≈ 0.87)</span>
    pen.<span class="fn">turn</span>(<span class="num">90</span>)           <span class="cm">// face right</span>
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">white</span>
    <span class="fn">drawCross</span>(pen: pen, size: size * <span class="num">0.2</span>)
}

<span class="cm">// Test</span>
<span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="fn">drawChurch</span>(pen: pen, size: <span class="num">80</span>)</pre>
          </div>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-04-a-church.png</span>
          <span class="img-hint">Image coming soon</span>
        </div>

        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Geometry — Modelling with Shapes</td><td>A church is modelled as a composite of three primitive shapes. Each component occupies a specific region — identifying those regions and computing their relative positions requires spatial reasoning and coordinate thinking.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 05 — Row of Churches
    ════════════════════════════════════════ -->
    <section id="s05">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>Row of Churches</h1>
        <p class="lead">Draw a row of <strong>five churches</strong>, each <code>10</code> points larger than the last. The first church should have <code>size: 40</code>, the last <code>size: 80</code>. Leave a gap of <code>20</code> points between each church.</p>
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      </div>
      <div class="article">
        <p>Because <code>drawChurch</code> always leaves the pen at the bottom-left of the church, facing right, moving to the start of the next church is straightforward.</p>

        <div class="code-wrap">
          <div class="code-header">
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          <pre><span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="kw">let</span> <span class="vr">gap</span> = <span class="num">20.0</span>

<span class="kw">for</span> <span class="vr">i</span> <span class="kw">in</span> <span class="num">0</span>...<span class="num">4</span> {
    <span class="kw">let</span> <span class="vr">size</span> = <span class="num">40.0</span> + <span class="tp">Double</span>(<span class="vr">i</span>) * <span class="num">10</span>
    <span class="cm">// draw one church then move pen right to the next start position</span>
    <span class="cm">// your code here</span>
}</pre>
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            <pre><span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="kw">let</span> <span class="vr">gap</span> = <span class="num">20.0</span>

<span class="kw">for</span> <span class="vr">i</span> <span class="kw">in</span> <span class="num">0</span>...<span class="num">4</span> {
    <span class="kw">let</span> <span class="vr">size</span> = <span class="num">40.0</span> + <span class="tp">Double</span>(<span class="vr">i</span>) * <span class="num">10</span>
    <span class="fn">drawChurch</span>(pen: pen, size: size)
    <span class="cm">// After drawChurch the pen is at bottom-left facing right.</span>
    <span class="cm">// Jump right by the church's width plus the gap.</span>
    <span class="fn">jump</span>(pen: pen, distance: size + gap)
}</pre>
          </div>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-05-row-of-churches.png</span>
          <span class="img-hint">Image coming soon</span>
        </div>

        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Functions &amp; Sequences</td><td>The church sizes form an arithmetic sequence: 40, 50, 60, 70, 80 — a common difference of 10. The loop variable <code>i</code> acts as the index; size = 40 + 10i is a linear function of i.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 06 — A Pretty House
    ════════════════════════════════════════ -->
    <section id="s06">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>A Pretty House</h1>
        <p class="lead">A house is more detailed than a church. Write <code>drawHouse(pen:size:)</code> that includes:</p>
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      <div class="article">
        <ul>
          <li>A rectangular <strong>body</strong> (width = <code>size</code>, height = <code>size * 0.75</code>)</li>
          <li>A triangular <strong>roof</strong> on top (call <code>drawRoof</code>)</li>
          <li>A rectangular <strong>door</strong> centred at the bottom (width = <code>size * 0.25</code>, height = <code>size * 0.4</code>)</li>
          <li>Two square <strong>windows</strong>, one on each side of the door (side = <code>size * 0.18</code>)</li>
        </ul>

        <p>Write helper functions <code>drawRect</code> and <code>drawWindow</code> first — it will make <code>drawHouse</code> much cleaner.</p>

        <div class="code-wrap">
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            <span class="code-lang">Swift</span>
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          </div>
          <pre><span class="cm">// Draw a rectangle (width × height), pen at bottom-left facing right.</span>
<span class="kw">func</span> <span class="fn">drawRect</span>(pen: <span class="tp">Pen</span>, width: <span class="tp">Double</span>, height: <span class="tp">Double</span>) {
    <span class="cm">// your code here</span>
}

<span class="kw">func</span> <span class="fn">drawHouse</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="kw">let</span> <span class="vr">bodyH</span> = size * <span class="num">0.75</span>
    <span class="kw">let</span> <span class="vr">doorW</span> = size * <span class="num">0.25</span>
    <span class="kw">let</span> <span class="vr">doorH</span> = size * <span class="num">0.4</span>
    <span class="kw">let</span> <span class="vr">winSide</span> = size * <span class="num">0.18</span>

    <span class="cm">// 1. Body</span>
    <span class="cm">// 2. Roof</span>
    <span class="cm">// 3. Door (centred horizontally at the bottom)</span>
    <span class="cm">// 4. Left window and right window</span>
    <span class="cm">// your code here</span>
}</pre>
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            <pre><span class="kw">func</span> <span class="fn">drawRect</span>(pen: <span class="tp">Pen</span>, width: <span class="tp">Double</span>, height: <span class="tp">Double</span>) {
    <span class="kw">for</span> _ <span class="kw">in</span> <span class="num">1</span>...<span class="num">2</span> {
        pen.<span class="fn">move</span>(width)
        pen.<span class="fn">turn</span>(<span class="num">90</span>)
        pen.<span class="fn">move</span>(height)
        pen.<span class="fn">turn</span>(<span class="num">90</span>)
    }
}

<span class="kw">func</span> <span class="fn">drawHouse</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="kw">let</span> <span class="vr">bodyH</span> = size * <span class="num">0.75</span>
    <span class="kw">let</span> <span class="vr">doorW</span> = size * <span class="num">0.25</span>
    <span class="kw">let</span> <span class="vr">doorH</span> = size * <span class="num">0.4</span>
    <span class="kw">let</span> <span class="vr">winSide</span> = size * <span class="num">0.18</span>

    <span class="cm">// ── 1. Body ───────────────────────────────────────────</span>
    pen.<span class="vr">color</span> = .<span class="vr">yellow</span>
    <span class="fn">drawRect</span>(pen: pen, width: size, height: bodyH)
    <span class="cm">// Pen back at bottom-left, facing right.</span>

    <span class="cm">// ── 2. Roof ────────────────────────────────────────────</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)
    pen.<span class="fn">move</span>(bodyH)
    pen.<span class="fn">turn</span>(<span class="num">90</span>)
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">red</span>
    <span class="fn">drawRoof</span>(pen: pen, base: size)
    <span class="cm">// Pen at top-right of roof base, facing right.</span>

    <span class="cm">// ── 3. Door (centred at bottom of body) ───────────────</span>
    <span class="cm">// Return to bottom-left, move right by (size - doorW) / 2</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(<span class="num">180</span>)
    pen.<span class="fn">move</span>(size)          <span class="cm">// back to top-left of roof base</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)           <span class="cm">// face down</span>
    pen.<span class="fn">move</span>(bodyH)          <span class="cm">// down to bottom-left of body</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)           <span class="cm">// face right</span>
    pen.<span class="fn">move</span>((size - doorW) / <span class="num">2</span>)
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">brown</span>
    <span class="fn">drawRect</span>(pen: pen, width: doorW, height: doorH)
    <span class="cm">// Pen at left side of door, facing right.</span>

    <span class="cm">// ── 4. Left window ────────────────────────────────────</span>
    <span class="cm">// Back to bottom-left, then position for left window</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(<span class="num">180</span>)
    pen.<span class="fn">move</span>((size - doorW) / <span class="num">2</span>)  <span class="cm">// back to bottom-left</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)
    pen.<span class="fn">move</span>(bodyH * <span class="num">0.45</span>)       <span class="cm">// up to window height</span>
    pen.<span class="fn">turn</span>(<span class="num">90</span>)
    pen.<span class="fn">move</span>(size * <span class="num">0.08</span>)         <span class="cm">// inset from left edge</span>
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">cyan</span>
    <span class="fn">drawSquare</span>(pen: pen, size: winSide)

    <span class="cm">// ── 5. Right window ───────────────────────────────────</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">move</span>(size * <span class="num">0.08</span> + winSide + doorW + size * <span class="num">0.08</span>)
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">cyan</span>
    <span class="fn">drawSquare</span>(pen: pen, size: winSide)
}

<span class="cm">// Test</span>
<span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="fn">drawHouse</span>(pen: pen, size: <span class="num">120</span>)</pre>
          </div>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-06-a-pretty-house.png</span>
          <span class="img-hint">Image coming soon</span>
        </div>

        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Geometry — Proportional Reasoning</td><td>All sub-components are proportional to <code>size</code>: the door is 25% as wide, windows are 18%, the body is 75% as tall. Scaling the house means scaling every component uniformly — a real-world application of ratio and proportion.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 07 — A Fence Post
    ════════════════════════════════════════ -->
    <section id="s07">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>A Fence Post</h1>
        <p class="lead">A classic picket fence post is a rectangle with a pointed top. Write <code>drawFencePost(pen:width:height:)</code> that draws the rectangular body and then calls <code>drawRoof</code> to add the pointed top.</p>
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      <div class="article">
        <p>The total visual height of the post is <code>height</code> (body) + the equilateral triangle's height above it. The body should have colour <code>.white</code>.</p>

        <div class="code-wrap">
          <div class="code-header">
            <span class="code-lang">Swift</span>
            <button class="code-copy" onclick="copyCode(this)">Copy</button>
          </div>
          <pre><span class="kw">func</span> <span class="fn">drawFencePost</span>(pen: <span class="tp">Pen</span>, width: <span class="tp">Double</span>, height: <span class="tp">Double</span>) {
    <span class="cm">// 1. Draw rectangular body (width × height)</span>
    <span class="cm">// 2. Move to top-left corner</span>
    <span class="cm">// 3. Call drawRoof(pen: pen, base: width)</span>
    <span class="cm">// 4. Return pen to original position at bottom-left, facing right</span>
    <span class="cm">// your code here</span>
}</pre>
        </div>

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            <pre><span class="kw">func</span> <span class="fn">drawFencePost</span>(pen: <span class="tp">Pen</span>, width: <span class="tp">Double</span>, height: <span class="tp">Double</span>) {
    <span class="cm">// ── 1. Rectangular body ──────────────────────────────</span>
    pen.<span class="vr">color</span> = .<span class="vr">white</span>
    <span class="fn">drawRect</span>(pen: pen, width: width, height: height)
    <span class="cm">// Pen at bottom-left, facing right.</span>

    <span class="cm">// ── 2. Pointed top ───────────────────────────────────</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)
    pen.<span class="fn">move</span>(height)
    pen.<span class="fn">turn</span>(<span class="num">90</span>)
    pen.<span class="fn">penDown</span>()
    <span class="fn">drawRoof</span>(pen: pen, base: width)
    <span class="cm">// Pen at top-right of body, facing right.</span>

    <span class="cm">// ── 3. Return to bottom-left ─────────────────────────</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(<span class="num">90</span>)
    pen.<span class="fn">move</span>(height)
    pen.<span class="fn">turn</span>(<span class="num">90</span>)
    pen.<span class="fn">move</span>(width)
    pen.<span class="fn">turn</span>(<span class="num">180</span>)
    pen.<span class="fn">penDown</span>()
}

<span class="cm">// Test</span>
<span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="fn">drawFencePost</span>(pen: pen, width: <span class="num">18</span>, height: <span class="num">60</span>)</pre>
          </div>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-07-a-fence-post.png</span>
          <span class="img-hint">Image coming soon</span>
        </div>

        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Geometry — Composite Figures</td><td>The total area of the fence post = area of rectangle + area of equilateral triangle. If rectangle height = h and width = w, the triangle height = w·√3/2. Calculating the total area requires combining both formulas.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 08 — A Whole Fence
    ════════════════════════════════════════ -->
    <section id="s08">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>A Whole Fence</h1>
        <p class="lead">Use a loop to draw a fence of <strong>8 posts</strong>. The posts should be <code>18</code> wide and <code>60</code> tall, with a <code>12</code>-point gap between them.</p>
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      <div class="article">
        <p>After drawing all the posts, go back and draw a <strong>horizontal rail</strong> across the middle of the posts (at half the post height) to complete the fence.</p>

        <div class="code-wrap">
          <div class="code-header">
            <span class="code-lang">Swift</span>
            <button class="code-copy" onclick="copyCode(this)">Copy</button>
          </div>
          <pre><span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="kw">let</span> <span class="vr">postW</span>: <span class="tp">Double</span> = <span class="num">18</span>
<span class="kw">let</span> <span class="vr">postH</span>: <span class="tp">Double</span> = <span class="num">60</span>
<span class="kw">let</span> <span class="vr">gap</span>: <span class="tp">Double</span>   = <span class="num">12</span>
<span class="kw">let</span> <span class="vr">count</span>         = <span class="num">8</span>

<span class="cm">// 1. Draw all posts in a row</span>
<span class="cm">// your code here</span>

<span class="cm">// 2. Return to left, climb to half height, draw horizontal rail</span>
<span class="cm">// your code here</span></pre>
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            <pre><span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="kw">let</span> <span class="vr">postW</span>: <span class="tp">Double</span> = <span class="num">18</span>
<span class="kw">let</span> <span class="vr">postH</span>: <span class="tp">Double</span> = <span class="num">60</span>
<span class="kw">let</span> <span class="vr">gap</span>: <span class="tp">Double</span>   = <span class="num">12</span>
<span class="kw">let</span> <span class="vr">count</span>         = <span class="num">8</span>

<span class="cm">// ── 1. Posts ─────────────────────────────────────────────</span>
<span class="kw">for</span> _ <span class="kw">in</span> <span class="num">1</span>...<span class="vr">count</span> {
    <span class="fn">drawFencePost</span>(pen: pen, width: postW, height: postH)
    <span class="fn">jump</span>(pen: pen, distance: postW + gap)
}
<span class="cm">// Pen is now to the right of the last post, facing right.</span>

<span class="cm">// ── 2. Rail ───────────────────────────────────────────────</span>
<span class="kw">let</span> <span class="vr">totalWidth</span> = <span class="tp">Double</span>(<span class="vr">count</span>) * (<span class="vr">postW</span> + <span class="vr">gap</span>) - <span class="vr">gap</span>
pen.<span class="fn">penUp</span>()
pen.<span class="fn">turn</span>(<span class="num">180</span>)                  <span class="cm">// face left</span>
pen.<span class="fn">move</span>(totalWidth + postW)    <span class="cm">// all the way back to start</span>
pen.<span class="fn">turn</span>(-<span class="num">90</span>)                  <span class="cm">// face up</span>
pen.<span class="fn">move</span>(postH / <span class="num">2</span>)            <span class="cm">// halfway up the post</span>
pen.<span class="fn">turn</span>(<span class="num">90</span>)                   <span class="cm">// face right</span>
pen.<span class="fn">penDown</span>()
pen.<span class="vr">color</span> = .<span class="vr">white</span>
pen.<span class="fn">move</span>(totalWidth)            <span class="cm">// draw the rail</span></pre>
          </div>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-08-a-whole-fence.png</span>
          <span class="img-hint">Image coming soon</span>
        </div>

        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Functions — Linear Expressions</td><td>Total fence width = n × (postW + gap) − gap. For 8 posts: 8 × 30 − 12 = 228. This is a linear function of n — the same expression that arises when summing fence sections or tiles in a pattern.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 09 — Broom Broom
    ════════════════════════════════════════ -->
    <section id="s09">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>Broom Broom</h1>
        <p class="lead">Every neighbourhood needs cars! Write <code>drawCar(pen:size:)</code> that draws a simple side-on car using three parts:</p>
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      </div>
      <div class="article">
        <ul>
          <li>A wide rectangular <strong>body</strong> (width = <code>size</code>, height = <code>size * 0.3</code>)</li>
          <li>A narrower rectangular <strong>cabin</strong> on top (width = <code>size * 0.55</code>, height = <code>size * 0.28</code>, inset <code>size * 0.18</code> from the left)</li>
          <li>Two square <strong>wheels</strong> (side = <code>size * 0.2</code>) at the bottom, positioned <code>size * 0.1</code> in from each end</li>
        </ul>

        <div class="code-wrap">
          <div class="code-header">
            <span class="code-lang">Swift</span>
            <button class="code-copy" onclick="copyCode(this)">Copy</button>
          </div>
          <pre><span class="kw">func</span> <span class="fn">drawCar</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="kw">let</span> <span class="vr">bodyH</span>   = size * <span class="num">0.3</span>
    <span class="kw">let</span> <span class="vr">cabinW</span>  = size * <span class="num">0.55</span>
    <span class="kw">let</span> <span class="vr">cabinH</span>  = size * <span class="num">0.28</span>
    <span class="kw">let</span> <span class="vr">cabinIn</span> = size * <span class="num">0.18</span>   <span class="cm">// inset from left</span>
    <span class="kw">let</span> <span class="vr">wheelS</span>  = size * <span class="num">0.2</span>
    <span class="kw">let</span> <span class="vr">wheelIn</span> = size * <span class="num">0.1</span>    <span class="cm">// wheel inset from each end</span>

    <span class="cm">// 1. Draw body</span>
    <span class="cm">// 2. Move to cabin start, draw cabin</span>
    <span class="cm">// 3. Draw left wheel, then right wheel</span>
    <span class="cm">// your code here</span>
}</pre>
        </div>

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            </div>
            <pre><span class="kw">func</span> <span class="fn">drawCar</span>(pen: <span class="tp">Pen</span>, size: <span class="tp">Double</span>) {
    <span class="kw">let</span> <span class="vr">bodyH</span>   = size * <span class="num">0.3</span>
    <span class="kw">let</span> <span class="vr">cabinW</span>  = size * <span class="num">0.55</span>
    <span class="kw">let</span> <span class="vr">cabinH</span>  = size * <span class="num">0.28</span>
    <span class="kw">let</span> <span class="vr">cabinIn</span> = size * <span class="num">0.18</span>
    <span class="kw">let</span> <span class="vr">wheelS</span>  = size * <span class="num">0.2</span>
    <span class="kw">let</span> <span class="vr">wheelIn</span> = size * <span class="num">0.1</span>

    <span class="cm">// ── 1. Body ──────────────────────────────────────────</span>
    pen.<span class="vr">color</span> = .<span class="vr">blue</span>
    <span class="fn">drawRect</span>(pen: pen, width: size, height: bodyH)
    <span class="cm">// Pen at bottom-left, facing right.</span>

    <span class="cm">// ── 2. Cabin ─────────────────────────────────────────</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)
    pen.<span class="fn">move</span>(bodyH)          <span class="cm">// up to top of body</span>
    pen.<span class="fn">turn</span>(<span class="num">90</span>)
    pen.<span class="fn">move</span>(cabinIn)         <span class="cm">// inset from left</span>
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">cyan</span>
    <span class="fn">drawRect</span>(pen: pen, width: cabinW, height: cabinH)
    <span class="cm">// Pen at cabin bottom-left (= start of cabin), facing right.</span>

    <span class="cm">// ── 3. Wheels ─────────────────────────────────────────</span>
    <span class="cm">// Return to body bottom-left first</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">turn</span>(<span class="num">180</span>)
    pen.<span class="fn">move</span>(cabinIn)         <span class="cm">// back to body left edge</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)
    pen.<span class="fn">move</span>(bodyH)           <span class="cm">// down to bottom of body</span>
    pen.<span class="fn">turn</span>(-<span class="num">90</span>)            <span class="cm">// face right</span>

    <span class="cm">// Left wheel (inset from left end)</span>
    pen.<span class="fn">move</span>(wheelIn)
    pen.<span class="fn">penDown</span>()
    pen.<span class="vr">color</span> = .<span class="vr">black</span>
    <span class="fn">drawSquare</span>(pen: pen, size: wheelS)
    <span class="cm">// Pen at left-wheel bottom-left, facing right.</span>

    <span class="cm">// Right wheel</span>
    pen.<span class="fn">penUp</span>()
    pen.<span class="fn">move</span>(size - <span class="num">2</span> * wheelIn - wheelS)  <span class="cm">// gap between wheels</span>
    pen.<span class="fn">penDown</span>()
    <span class="fn">drawSquare</span>(pen: pen, size: wheelS)
}

<span class="cm">// Test</span>
<span class="kw">let</span> <span class="vr">pen</span> = <span class="tp">Pen</span>()
<span class="fn">drawCar</span>(pen: pen, size: <span class="num">150</span>)</pre>
          </div>
        </div>

        <div class="img-placeholder">
          <span class="img-icon">📷</span>
          <span class="img-name">06-09-broom-broom.png</span>
          <span class="img-hint">Image coming soon</span>
        </div>

        <div class="im-table-wrap">
          <div class="im-table-header">IM1 Curriculum Connection</div>
          <table class="im-table">
            <thead><tr><th>Standard</th><th>Connection</th></tr></thead>
            <tbody>
              <tr><td>Geometry — Scale and Proportion</td><td>Every dimension of the car is a fixed proportion of <code>size</code>. Changing <code>size</code> scales all components simultaneously — a direct application of scaling figures and maintaining ratios. The gap between wheels = size − 2·wheelIn − wheelS is an algebraic expression derived from fitting shapes within a bounded space.</td></tr>
            </tbody>
          </table>
        </div>
      </div>
    </section>

    <!-- ════════════════════════════════════════
         SECTION 10 — Neighbourhood Scene
    ════════════════════════════════════════ -->
    <section id="s10">
      <div class="section-hero">
        <span class="section-tag exercise">◆ Exercise</span>
        <h1>Neighbourhood Scene</h1>
        <p class="lead">The grand finale! Use every function you have written to draw a complete suburban neighbourhood. Your scene must include at least:</p>
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      </div>
      <div class="article">
        <ul>
          <li>Two <strong>houses</strong> of different sizes</li>
          <li>One <strong>church</strong></li>
          <li>A <strong>fence</strong> in front of one house</li>
          <li>One <strong>car</strong> on the street</li>
        </ul>

        <p>Plan your scene on paper first — sketch where each building goes, estimate the sizes, and work out how far apart they should be. Then translate that plan into code, one component at a time.</p>

        <div class="callout">
          <strong>Tip:</strong> Use the <code>jump</code> helper to reposition the pen between buildings. Remember that after each <code>draw…</code> call the pen returns to the bottom-left of that component, facing right — so jumping right by the component's width gets you to the next gap.
        </div>