<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: transparent;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      user-select: none;
    }

    .main-grid {
      width: 100%;
      max-width: 520px;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
    }

    .section-title {
      grid-column: 1 / -1;
      font-size: 13px;
      font-weight: 700;
      letter-spacing: 0.2px;
      text-transform: uppercase;
      padding: 4px 0 2px;
      border-bottom: 2px solid #f1f5f9;
      display: flex;
      justify-content: space-between;
      align-items: baseline;
    }

    .section-title.odd {
      color: #b45309;
      border-bottom-color: #fde68a;
    }

    .section-title.even {
      color: #4338ca;
      border-bottom-color: #ddd6fe;
      margin-top: 4px;
    }

    .shape-card {
      display: flex;
      flex-direction: column;
      align-items: center;
      background: #fafafc;
      border-radius: 8px;
      padding: 8px 6px;
    }

    .svg-wrap {
      width: 100%;
      max-width: 130px;
      aspect-ratio: 1;
    }

    svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }

    .poly-bg {
      fill: #f8fafc;
      stroke: #94a3b8;
      stroke-width: 2;
      stroke-linejoin: round;
    }

    .sym-line {
      stroke-width: 2;
      stroke-linecap: round;
      stroke-dasharray: 4 3;
      transition: opacity 0.25s ease, stroke-width 0.25s ease;
    }

    .line-vm {
      stroke: #d97706;
    }

    .line-vv {
      stroke: #7c3aed;
    }

    .line-mm {
      stroke: #0284c7;
    }

    .marker-v {
      fill: #475569;
      transition: transform 0.2s ease;
    }

    .marker-m {
      fill: #94a3b8;
      stroke: #ffffff;
      stroke-width: 1;
    }

    .dimmed {
      opacity: 0.15 !important;
    }

    .shape-label {
      font-size: 13px;
      font-weight: 700;
      margin-top: 4px;
      color: #0f172a;
    }

    .shape-sub {
      font-size: 11px;
      font-weight: 600;
      color: #64748b;
      margin-top: 1px;
      text-align: center;
    }

    .legend-bar {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 8px;
      margin-top: 10px;
      max-width: 520px;
      width: 100%;
    }

    .legend-btn {
      appearance: none;
      border: 1px solid #e2e8f0;
      background: #ffffff;
      padding: 4px 10px;
      border-radius: 999px;
      font-size: 12px;
      font-weight: 600;
      color: #334155;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background 0.2s, border-color 0.2s, color 0.2s;
    }

    .legend-btn:hover {
      background: #f8fafc;
    }

    .legend-btn.active {
      background: #0f172a;
      border-color: #0f172a;
      color: #ffffff;
    }

    .swatch {
      width: 14px;
      height: 3px;
      border-radius: 2px;
    }

    .swatch-vm { background: #d97706; }
    .swatch-vv { background: #7c3aed; }
    .swatch-mm { background: #0284c7; }
  </style>
</head>
<body>

  <div class="main-grid">
    
    <div class="section-title odd">
      <span>Odd Sides (n = 3, 5)</span>
      <span style="font-size:11px; font-weight:600;">Vertex ➔ Midpoint</span>
    </div>

    
    <div class="shape-card">
      <div class="svg-wrap">
        <svg viewBox="0 0 100 100">
          <polygon class="poly-bg" points="50,14 84.64,74 15.36,74" />
          
          
          <line class="sym-line line-vm" x1="50" y1="6" x2="50" y2="82" />
          
          <line class="sym-line line-vm" x1="91.57" y1="78" x2="25.75" y2="40" />
          
          <line class="sym-line line-vm" x1="8.43" y1="78" x2="74.25" y2="40" />

          
          <circle class="marker-m" cx="50" cy="74" r="2.5" />
          <circle class="marker-m" cx="32.68" cy="44" r="2.5" />
          <circle class="marker-m" cx="67.32" cy="44" r="2.5" />

          
          <circle class="marker-v" cx="50" cy="14" r="3.5" />
          <circle class="marker-v" cx="84.64" cy="74" r="3.5" />
          <circle class="marker-v" cx="15.36" cy="74" r="3.5" />
        </svg>
      </div>
      <div class="shape-label">Triangle (n = 3)</div>
      <div class="shape-sub">3 lines</div>
    </div>

    
    <div class="shape-card">
      <div class="svg-wrap">
        <svg viewBox="0 0 100 100">
          
          
          
          <polygon class="poly-bg" points="50,14 86.14,40.26 72.34,82.74 27.66,82.74 13.86,40.26" />
          
          
          
          <line class="sym-line line-vm" x1="50" y1="8" x2="50" y2="88" />
          
          <line class="sym-line line-vm" x1="91.8" y1="36.1" x2="15.1" y2="65.6" />
          
          <line class="sym-line line-vm" x1="75.8" y1="89.3" x2="25.5" y2="18.5" />
          
          <line class="sym-line line-vm" x1="24.2" y1="89.3" x2="74.5" y2="18.5" />
          
          <line class="sym-line line-vm" x1="8.2" y1="36.1" x2="84.9" y2="65.6" />

          
          <circle class="marker-m" cx="50" cy="82.74" r="2.2" />
          <circle class="marker-m" cx="20.76" cy="61.5" r="2.2" />
          <circle class="marker-m" cx="31.93" cy="27.13" r="2.2" />
          <circle class="marker-m" cx="68.07" cy="27.13" r="2.2" />
          <circle class="marker-m" cx="79.24" cy="61.5" r="2.2" />

          
          <circle class="marker-v" cx="50" cy="14" r="3" />
          <circle class="marker-v" cx="86.14" cy="40.26" r="3" />
          <circle class="marker-v" cx="72.34" cy="82.74" r="3" />
          <circle class="marker-v" cx="27.66" cy="82.74" r="3" />
          <circle class="marker-v" cx="13.86" cy="40.26" r="3" />
        </svg>
      </div>
      <div class="shape-label">Pentagon (n = 5)</div>
      <div class="shape-sub">5 lines</div>
    </div>

    
    <div class="section-title even">
      <span>Even Sides (n = 4, 6)</span>
      <span style="font-size:11px; font-weight:600;">Vertex ➔ Vertex &amp; Mid ➔ Mid</span>
    </div>

    
    <div class="shape-card">
      <div class="svg-wrap">
        <svg viewBox="0 0 100 100">
          <polygon class="poly-bg" points="20,20 80,20 80,80 20,80" />
          
          
          <line class="sym-line line-mm" x1="50" y1="12" x2="50" y2="88" />
          <line class="sym-line line-mm" x1="12" y1="50" x2="88" y2="50" />

          
          <line class="sym-line line-vv" x1="14" y1="14" x2="86" y2="86" />
          <line class="sym-line line-vv" x1="86" y1="14" x2="14" y2="86" />

          
          <circle class="marker-m" cx="50" cy="20" r="2.5" />
          <circle class="marker-m" cx="80" cy="50" r="2.5" />
          <circle class="marker-m" cx="50" cy="80" r="2.5" />
          <circle class="marker-m" cx="20" cy="50" r="2.5" />

          
          <circle class="marker-v" cx="20" cy="20" r="3.2" />
          <circle class="marker-v" cx="80" cy="20" r="3.2" />
          <circle class="marker-v" cx="80" cy="80" r="3.2" />
          <circle class="marker-v" cx="20" cy="80" r="3.2" />
        </svg>
      </div>
      <div class="shape-label">Square (n = 4)</div>
      <div class="shape-sub">2 diag + 2 mid = 4 lines</div>
    </div>

    
    <div class="shape-card">
      <div class="svg-wrap">
        <svg viewBox="0 0 100 100">
          
          
          <polygon class="poly-bg" points="50,14 81.18,32 81.18,68 50,86 18.82,68 18.82,32" />

          
          <line class="sym-line line-mm" x1="12" y1="50" x2="88" y2="50" />
          <line class="sym-line line-mm" x1="30" y1="18" x2="70" y2="82" />
          <line class="sym-line line-mm" x1="70" y1="18" x2="30" y2="82" />

          
          <line class="sym-line line-vv" x1="50" y1="8" x2="50" y2="92" />
          <line class="sym-line line-vv" x1="85.5" y1="29.5" x2="14.5" y2="70.5" />
          <line class="sym-line line-vv" x1="85.5" y1="70.5" x2="14.5" y2="29.5" />

          
          <circle class="marker-m" cx="65.59" cy="23" r="2.2" />
          <circle class="marker-m" cx="81.18" cy="50" r="2.2" />
          <circle class="marker-m" cx="65.59" cy="77" r="2.2" />
          <circle class="marker-m" cx="34.41" cy="77" r="2.2" />
          <circle class="marker-m" cx="18.82" cy="50" r="2.2" />
          <circle class="marker-m" cx="34.41" cy="23" r="2.2" />

          
          <circle class="marker-v" cx="50" cy="14" r="3" />
          <circle class="marker-v" cx="81.18" cy="32" r="3" />
          <circle class="marker-v" cx="81.18" cy="68" r="3" />
          <circle class="marker-v" cx="50" cy="86" r="3" />
          <circle class="marker-v" cx="18.82" cy="68" r="3" />
          <circle class="marker-v" cx="18.82" cy="32" r="3" />
        </svg>
      </div>
      <div class="shape-label">Hexagon (n = 6)</div>
      <div class="shape-sub">3 diag + 3 mid = 6 lines</div>
    </div>
  </div>

  
  <div class="legend-bar">
    <button class="legend-btn active" data-filter="all" onclick="filterLines('all')">
      Show All
    </button>
    <button class="legend-btn" data-filter="vm" onclick="filterLines('vm')">
      <span class="swatch swatch-vm"></span>
      <span>Vertex ➔ Mid</span>
    </button>
    <button class="legend-btn" data-filter="vv" onclick="filterLines('vv')">
      <span class="swatch swatch-vv"></span>
      <span>Vertex ➔ Vertex</span>
    </button>
    <button class="legend-btn" data-filter="mm" onclick="filterLines('mm')">
      <span class="swatch swatch-mm"></span>
      <span>Mid ➔ Mid</span>
    </button>
  </div>

  <script>
    function filterLines(type) {
      const buttons = document.querySelectorAll('.legend-btn');
      buttons.forEach(btn => {
        if (btn.getAttribute('data-filter') === type) {
          btn.classList.add('active');
        } else {
          btn.classList.remove('active');
        }
      });

      const vm = document.querySelectorAll('.line-vm');
      const vv = document.querySelectorAll('.line-vv');
      const mm = document.querySelectorAll('.line-mm');

      if (type === 'all') {
        vm.forEach(el => el.classList.remove('dimmed'));
        vv.forEach(el => el.classList.remove('dimmed'));
        mm.forEach(el => el.classList.remove('dimmed'));
      } else if (type === 'vm') {
        vm.forEach(el => el.classList.remove('dimmed'));
        vv.forEach(el => el.classList.add('dimmed'));
        mm.forEach(el => el.classList.add('dimmed'));
      } else if (type === 'vv') {
        vm.forEach(el => el.classList.add('dimmed'));
        vv.forEach(el => el.classList.remove('dimmed'));
        mm.forEach(el => el.classList.add('dimmed'));
      } else if (type === 'mm') {
        vm.forEach(el => el.classList.add('dimmed'));
        vv.forEach(el => el.classList.add('dimmed'));
        mm.forEach(el => el.classList.remove('dimmed'));
      }
    }
  </script>
</body>
</html>

Identifying Vertical, Horizontal, and Diagonal Lines of Symmetry

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <title>Square Lines of Symmetry</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 12px 10px;
      user-select: none;
    }

    .header-badge {
      font-size: 13px;
      font-weight: 700;
      letter-spacing: 0.5px;
      text-transform: uppercase;
      color: #64748b;
      margin-bottom: 4px;
    }

    .stage-container {
      position: relative;
      width: 100%;
      max-width: 280px;
      aspect-ratio: 1 / 1;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }

    /* Square Base */
    .base-square {
      fill: #f8fafc;
      stroke: #cbd5e1;
      stroke-width: 2.5;
      stroke-linejoin: round;
    }

    /* Halves Shading */
    .half-shape {
      opacity: 0;
      transition: opacity 0.35s ease, transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
      transform-origin: center;
    }

    .half-shape.active {
      opacity: 0.35;
    }

    /* Symmetry Lines */
    .sym-line {
      stroke-dasharray: 6 5;
      stroke-width: 2.5;
      stroke-linecap: round;
      opacity: 0.35;
      transition: opacity 0.3s ease, stroke-width 0.3s ease;
    }

    .sym-line.active {
      opacity: 1;
      stroke-width: 4;
    }

    .line-v { stroke: #ef4444; }
    .line-h { stroke: #2563eb; }
    .line-d1 { stroke: #f97316; }
    .line-d2 { stroke: #10b981; }

    /* Corner & Midpoint Dots */
    .anchor-dot {
      fill: #94a3b8;
      transition: fill 0.3s ease, transform 0.3s ease;
    }

    /* Controls Panel */
    .controls {
      display: flex;
      flex-direction: column;
      gap: 8px;
      width: 100%;
      max-width: 330px;
      margin-top: 6px;
    }

    .btn-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 6px;
    }

    .btn-step {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      font-size: 13px;
      font-weight: 600;
      padding: 8px 6px;
      border-radius: 8px;
      border: 1.5px solid #e2e8f0;
      background: #f8fafc;
      color: #475569;
      cursor: pointer;
      box-shadow: none;
      transition: background 0.2s, border-color 0.2s, color 0.2s;
    }

    .btn-step .swatch {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      flex-shrink: 0;
    }

    .btn-step[data-step="0"] .swatch { background: #ef4444; }
    .btn-step[data-step="1"] .swatch { background: #2563eb; }
    .btn-step[data-step="2"] .swatch { background: #f97316; }
    .btn-step[data-step="3"] .swatch { background: #10b981; }

    .btn-step.active[data-step="0"] {
      border-color: #ef4444;
      background: #fef2f2;
      color: #b91c1c;
    }
    .btn-step.active[data-step="1"] {
      border-color: #2563eb;
      background: #eff6ff;
      color: #1d4ed8;
    }
    .btn-step.active[data-step="2"] {
      border-color: #f97316;
      background: #fff7ed;
      color: #c2410c;
    }
    .btn-step.active[data-step="3"] {
      border-color: #10b981;
      background: #ecfdf5;
      color: #047857;
    }

    .playback-bar {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 12px;
      margin-top: 2px;
    }

    .play-btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      background: none;
      border: 1px solid #cbd5e1;
      border-radius: 20px;
      padding: 3px 12px;
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      cursor: pointer;
      transition: background 0.2s, color 0.2s;
    }

    .play-btn:hover {
      background: #f1f5f9;
      color: #1e2945;
    }
  </style>
</head>
<body>

  <div class="header-badge">Square · 4 Lines of Symmetry</div>

  <div class="stage-container">
    <svg viewBox="0 0 240 240">
      
      <rect class="base-square" x="30" y="30" width="180" height="180" rx="4" />

      
      
      <g id="fold-0">
        <rect class="half-shape" x="30" y="30" width="90" height="180" fill="#ef4444" />
        <rect class="half-shape" x="120" y="30" width="90" height="180" fill="#f87171" />
      </g>

      
      <g id="fold-1">
        <rect class="half-shape" x="30" y="30" width="180" height="90" fill="#2563eb" />
        <rect class="half-shape" x="30" y="120" width="180" height="90" fill="#60a5fa" />
      </g>

      
      <g id="fold-2">
        <polygon class="half-shape" points="30,30 210,30 210,210" fill="#f97316" />
        <polygon class="half-shape" points="30,30 30,210 210,210" fill="#fb923c" />
      </g>

      
      <g id="fold-3">
        <polygon class="half-shape" points="30,30 210,30 30,210" fill="#10b981" />
        <polygon class="half-shape" points="210,30 210,210 30,210" fill="#34d399" />
      </g>

      
      <rect x="30" y="30" width="180" height="180" fill="none" stroke="#475569" stroke-width="2" rx="4" />

      
      
      <line id="line-1" class="sym-line line-h" x1="16" y1="120" x2="224" y2="120" />
      
      <line id="line-2" class="sym-line line-d1" x1="20" y1="20" x2="220" y2="220" />
      
      <line id="line-3" class="sym-line line-d2" x1="20" y1="220" x2="220" y2="20" />
      
      <line id="line-0" class="sym-line line-v" x1="120" y1="16" x2="120" y2="224" />

      
      <circle cx="120" cy="120" r="4.5" fill="#1e2945" />
    </svg>
  </div>

  <div class="controls">
    <div class="btn-grid">
      <button class="btn-step" data-step="0">
        <span class="swatch"></span>
        Vertical
      </button>
      <button class="btn-step" data-step="1">
        <span class="swatch"></span>
        Horizontal
      </button>
      <button class="btn-step" data-step="2">
        <span class="swatch"></span>
        Diagonal ↘
      </button>
      <button class="btn-step" data-step="3">
        <span class="swatch"></span>
        Diagonal ↗
      </button>
    </div>

    <div class="playback-bar">
      <button id="togglePlay" class="play-btn">⏸ Pause</button>
    </div>
  </div>

  <script>
    let currentStep = 0;
    let isPlaying = true;
    let timer = null;

    const buttons = document.querySelectorAll('.btn-step');
    const playBtn = document.getElementById('togglePlay');

    function setStep(index) {
      currentStep = index;

      // Update buttons
      buttons.forEach((btn, i) => {
        btn.classList.toggle('active', i === index);
      });

      // Update symmetry lines
      for (let i = 0; i < 4; i++) {
        const line = document.getElementById(`line-${i}`);
        if (line) {
          line.classList.toggle('active', i === index);
        }
      }

      // Update fold halves
      for (let i = 0; i < 4; i++) {
        const foldGroup = document.getElementById(`fold-${i}`);
        if (foldGroup) {
          const shapes = foldGroup.querySelectorAll('.half-shape');
          shapes.forEach(s => s.classList.toggle('active', i === index));
        }
      }
    }

    function nextStep() {
      setStep((currentStep + 1) % 4);
    }

    function startAutoPlay() {
      clearInterval(timer);
      timer = setInterval(nextStep, 3000);
      isPlaying = true;
      playBtn.textContent = '⏸ Pause';
    }

    function stopAutoPlay() {
      clearInterval(timer);
      isPlaying = false;
      playBtn.textContent = '▶ Auto Play';
    }

    // Interactive button clicks
    buttons.forEach((btn) => {
      btn.addEventListener('click', () => {
        const step = parseInt(btn.getAttribute('data-step'), 10);
        setStep(step);
        stopAutoPlay();
      });
    });

    // Play/Pause button
    playBtn.addEventListener('click', () => {
      if (isPlaying) {
        stopAutoPlay();
      } else {
        nextStep();
        startAutoPlay();
      }
    });

    // Initialize Step 0 & Start
    setStep(0);
    startAutoPlay();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px;
      min-height: 100%;
      user-select: none;
    }

    .panels {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
      max-width: 600px;
      flex: 1;
    }

    .panel {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px 8px 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
    }

    .panel-title {
      font-size: 15px;
      font-weight: 700;
      color: #334155;
      margin-bottom: 4px;
    }

    .svg-container {
      width: 100%;
      max-width: 220px;
      height: 180px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }

    .badge {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      font-size: 13px;
      font-weight: 700;
      padding: 6px 10px;
      border-radius: 20px;
      margin-top: 6px;
      text-align: center;
      line-height: 1.2;
    }

    .badge-success {
      background: #dcfce7;
      color: #15803d;
      border: 1px solid #86efac;
    }

    .badge-error {
      background: #fee2e2;
      color: #b91c1c;
      border: 1px solid #fca5a5;
    }

    .controls {
      display: flex;
      gap: 8px;
      margin-top: 10px;
    }

    .btn {
      appearance: none;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #475569;
      padding: 6px 16px;
      font-size: 13px;
      font-weight: 600;
      border-radius: 8px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: all 0.2s ease;
    }

    .btn.active {
      background: #22b7ff;
      border-color: #0284c7;
      color: #ffffff;
      box-shadow: 0 2px 4px rgba(34, 183, 255, 0.25);
    }

    .overhang-label {
      font-size: 11px;
      font-weight: 700;
      fill: #dc2626;
    }
  </style>
</head>
<body>

  <div class="panels">
    
    <div class="panel">
      <div class="panel-title">Square</div>
      <div class="svg-container">
        <svg viewBox="0 0 160 170">
          
          <polygon points="15,20 15,140 135,140" fill="#e0f2fe" stroke="#0284c7" stroke-width="2" />
          
          
          <line x1="15" y1="20" x2="135" y2="140" stroke="#94a3b8" stroke-width="2" stroke-dasharray="4 4" />
          
          
          <polygon id="sqFlap" points="15,20 135,20 135,140" fill="rgba(99, 102, 241, 0.3)" stroke="#6366f1" stroke-width="2" />
          
          
          <circle id="sqDot" cx="135" cy="20" r="4" fill="#4f46e5" />
        </svg>
      </div>
      <div class="badge badge-success">✓ Matches!</div>
    </div>

    
    <div class="panel">
      <div class="panel-title">Rectangle</div>
      <div class="svg-container">
        <svg viewBox="0 0 180 170">
          
          <polygon points="15,25 15,115 165,115" fill="#e0f2fe" stroke="#0284c7" stroke-width="2" />
          
          
          <line x1="15" y1="25" x2="165" y2="115" stroke="#94a3b8" stroke-width="2" stroke-dasharray="4 4" />
          
          
          <polygon id="rectFlap" points="15,25 165,25 165,115" fill="rgba(239, 68, 68, 0.25)" stroke="#ef4444" stroke-width="2" />
          
          
          <g id="rectMismatch" opacity="0">
            <circle cx="85.6" cy="157.4" r="8" fill="none" stroke="#dc2626" stroke-width="2" stroke-dasharray="2 2" />
            <circle cx="15" cy="115" r="8" fill="none" stroke="#dc2626" stroke-width="2" stroke-dasharray="2 2" />
            <text x="96" y="161" class="overhang-label">Overhang</text>
          </g>
          
          
          <circle id="rectDot" cx="165" cy="25" r="4" fill="#dc2626" />
        </svg>
      </div>
      <div class="badge badge-error">✗ Corners do not match!</div>
    </div>
  </div>

  <div class="controls">
    <button id="btnUnfold" class="btn">📄 Unfold</button>
    <button id="btnFold" class="btn active">📐 Fold Diagonal</button>
  </div>

  <script>
    const sqFlap = document.getElementById('sqFlap');
    const sqDot = document.getElementById('sqDot');
    const rectFlap = document.getElementById('rectFlap');
    const rectDot = document.getElementById('rectDot');
    const rectMismatch = document.getElementById('rectMismatch');
    const btnFold = document.getElementById('btnFold');
    const btnUnfold = document.getElementById('btnUnfold');

    // Square coordinates:
    // Unfolded corner: (135, 20), Folded corner: (15, 140)
    const sqP0 = { x: 135, y: 20 };
    const sqP1 = { x: 15, y: 140 };

    // Rectangle coordinates:
    // Unfolded corner: (165, 25), Folded corner: (85.6, 157.4)
    const rectP0 = { x: 165, y: 25 };
    const rectP1 = { x: 85.6, y: 157.4 };

    let currentT = 1;
    let targetT = 1;
    let animId = null;

    function render(t) {
      // Ease function
      const ease = t < 0.5 ? 2 * t * t : 1 - Math.pow(-2 * t + 2, 2) / 2;

      // Update square flap
      const sqX = sqP0.x + (sqP1.x - sqP0.x) * ease;
      const sqY = sqP0.y + (sqP1.y - sqP0.y) * ease;
      sqFlap.setAttribute('points', `15,20 ${sqX},${sqY} 135,140`);
      sqDot.setAttribute('cx', sqX);
      sqDot.setAttribute('cy', sqY);

      // Update rectangle flap
      const rectX = rectP0.x + (rectP1.x - rectP0.x) * ease;
      const rectY = rectP0.y + (rectP1.y - rectP0.y) * ease;
      rectFlap.setAttribute('points', `15,25 ${rectX},${rectY} 165,115`);
      rectDot.setAttribute('cx', rectX);
      rectDot.setAttribute('cy', rectY);

      // Show overhang markings as fold finishes
      const mismatchOpacity = Math.max(0, (ease - 0.7) / 0.3);
      rectMismatch.setAttribute('opacity', mismatchOpacity);
    }

    function animate() {
      const diff = targetT - currentT;
      if (Math.abs(diff) < 0.01) {
        currentT = targetT;
        render(currentT);
        animId = null;
        return;
      }
      currentT += diff * 0.15;
      render(currentT);
      animId = requestAnimationFrame(animate);
    }

    function setFoldState(folded) {
      targetT = folded ? 1 : 0;
      if (folded) {
        btnFold.classList.add('active');
        btnUnfold.classList.remove('active');
      } else {
        btnUnfold.classList.add('active');
        btnFold.classList.remove('active');
      }
      if (!animId) {
        animId = requestAnimationFrame(animate);
      }
    }

    btnFold.addEventListener('click', () => setFoldState(true));
    btnUnfold.addEventListener('click', () => setFoldState(false));

    // Initial render folded
    render(1);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 12px;
      user-select: none;
    }

    .main-grid {
      display: flex;
      flex-direction: row;
      justify-content: center;
      align-items: center;
      gap: 16px;
      width: 100%;
      max-width: 480px;
      flex: 1;
    }

    .shape-card {
      flex: 1;
      display: flex;
      flex-direction: column;
      align-items: center;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 14px;
      padding: 10px 8px 12px;
      position: relative;
    }

    .shape-title {
      font-size: 13px;
      font-weight: 700;
      color: #475569;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      margin-bottom: 6px;
    }

    .stage-wrap {
      width: 130px;
      height: 130px;
      position: relative;
      perspective: 700px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .shape-box {
      width: 130px;
      height: 130px;
      position: relative;
    }

    /* Left half (stationary) */
    .half-left {
      position: absolute;
      left: 0;
      top: 0;
      width: 65px;
      height: 130px;
      overflow: hidden;
      z-index: 1;
    }

    .half-left svg {
      position: absolute;
      left: 0;
      top: 0;
      width: 130px;
      height: 130px;
    }

    /* Right half (folding) */
    .half-right-hinge {
      position: absolute;
      left: 65px;
      top: 0;
      width: 65px;
      height: 130px;
      transform-origin: left center;
      transform-style: preserve-3d;
      z-index: 2;
      transition: transform 0.05s linear;
      will-change: transform;
    }

    .half-right-clip {
      width: 65px;
      height: 130px;
      overflow: hidden;
      position: relative;
      backface-visibility: visible;
    }

    .half-right-clip svg {
      position: absolute;
      left: -65px;
      top: 0;
      width: 130px;
      height: 130px;
    }

    /* Dashed mirror line */
    .mirror-line {
      position: absolute;
      left: 65px;
      top: -4px;
      bottom: -4px;
      width: 2px;
      background: repeating-linear-gradient(
        to bottom,
        #4f46e5 0,
        #4f46e5 5px,
        transparent 5px,
        transparent 9px
      );
      z-index: 5;
      pointer-events: none;
      transform: translateX(-50%);
    }

    .labels-row {
      display: flex;
      justify-content: space-between;
      width: 100%;
      max-width: 130px;
      margin-top: 8px;
      font-size: 11px;
      font-weight: 600;
    }

    .label-left {
      color: #64748b;
      text-align: left;
    }

    .label-right {
      color: #64748b;
      text-align: right;
    }

    /* Match badge */
    .match-badge {
      font-size: 11px;
      font-weight: 700;
      color: #4f46e5;
      background: #eef2ff;
      border: 1px solid #c7d2fe;
      border-radius: 6px;
      padding: 3px 8px;
      margin-top: 6px;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      opacity: 0;
      transform: scale(0.9);
      transition: opacity 0.2s ease, transform 0.2s ease;
    }

    .match-badge.visible {
      opacity: 1;
      transform: scale(1);
    }

    /* Control panel */
    .controls-panel {
      width: 100%;
      max-width: 480px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 14px;
      padding: 10px 14px;
      display: flex;
      flex-direction: column;
      gap: 8px;
      margin-top: 8px;
    }

    .slider-row {
      display: flex;
      align-items: center;
      gap: 10px;
      width: 100%;
    }

    .slider-row span {
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      min-width: 52px;
    }

    input[type="range"] {
      flex: 1;
      height: 6px;
      border-radius: 4px;
      background: #e2e8f0;
      outline: none;
      -webkit-appearance: none;
      cursor: pointer;
    }

    input[type="range"]::-webkit-slider-thumb {
      -webkit-appearance: none;
      width: 18px;
      height: 18px;
      border-radius: 50%;
      background: #4f46e5;
      border: 2px solid #ffffff;
      box-shadow: 0 1px 4px rgba(0,0,0,0.25);
      cursor: pointer;
    }

    input[type="range"]::-moz-range-thumb {
      width: 18px;
      height: 18px;
      border-radius: 50%;
      background: #4f46e5;
      border: 2px solid #ffffff;
      box-shadow: 0 1px 4px rgba(0,0,0,0.25);
      cursor: pointer;
    }

    .btn-row {
      display: flex;
      justify-content: center;
      gap: 8px;
    }

    .ctrl-btn {
      flex: 1;
      padding: 6px 10px;
      font-size: 12px;
      font-weight: 600;
      border-radius: 8px;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #334155;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 5px;
      transition: background 0.15s, border-color 0.15s;
    }

    .ctrl-btn.active {
      background: #4f46e5;
      color: #ffffff;
      border-color: #4f46e5;
    }
  </style>
</head>
<body>

  <div class="main-grid">
    
    <div class="shape-card">
      <div class="shape-title">Heart</div>
      <div class="stage-wrap">
        <div class="shape-box">
          <div class="mirror-line"></div>
          
          <div class="half-left">
            <svg viewBox="0 0 130 130">
              <path d="M 65,34 C 65,19 46,14 32,24 C 16,36 16,62 35,84 L 65,114 L 95,84 C 114,62 114,36 98,24 C 84,14 65,19 65,34 Z"
                    fill="#fb7185" stroke="#e11d48" stroke-width="2.5" stroke-linejoin="round"/>
            </svg>
          </div>
          
          <div class="half-right-hinge" id="heartRight">
            <div class="half-right-clip">
              <svg viewBox="0 0 130 130">
                <path d="M 65,34 C 65,19 46,14 32,24 C 16,36 16,62 35,84 L 65,114 L 95,84 C 114,62 114,36 98,24 C 84,14 65,19 65,34 Z"
                      fill="#f43f5e" stroke="#e11d48" stroke-width="2.5" stroke-linejoin="round"/>
              </svg>
            </div>
          </div>
        </div>
      </div>
      <div class="labels-row">
        <span class="label-left">Left half</span>
        <span class="label-right">Right half</span>
      </div>
      <div class="match-badge" id="heartBadge">✓ Exact match!</div>
    </div>

    
    <div class="shape-card">
      <div class="shape-title">Letter A</div>
      <div class="stage-wrap">
        <div class="shape-box">
          <div class="mirror-line"></div>
          
          <div class="half-left">
            <svg viewBox="0 0 130 130">
              <path d="M 65,16 L 108,114 L 88,114 L 78,88 L 52,88 L 42,114 L 22,114 Z M 65,46 L 57,72 L 73,72 Z"
                    fill="#a855f7" stroke="#7e22ce" stroke-width="2.5" stroke-linejoin="round"/>
            </svg>
          </div>
          
          <div class="half-right-hinge" id="aRight">
            <div class="half-right-clip">
              <svg viewBox="0 0 130 130">
                <path d="M 65,16 L 108,114 L 88,114 L 78,88 L 52,88 L 42,114 L 22,114 Z M 65,46 L 57,72 L 73,72 Z"
                      fill="#9333ea" stroke="#7e22ce" stroke-width="2.5" stroke-linejoin="round"/>
              </svg>
            </div>
          </div>
        </div>
      </div>
      <div class="labels-row">
        <span class="label-left">Left half</span>
        <span class="label-right">Right half</span>
      </div>
      <div class="match-badge" id="aBadge">✓ Exact match!</div>
    </div>
  </div>

  
  <div class="controls-panel">
    <div class="slider-row">
      <span>Open</span>
      <input type="range" id="foldSlider" min="0" max="180" value="0" step="1" aria-label="Fold angle">
      <span>Folded</span>
    </div>
    <div class="btn-row">
      <button class="ctrl-btn active" id="playBtn">⏸ Pause</button>
      <button class="ctrl-btn" id="openBtn">Open</button>
      <button class="ctrl-btn" id="foldBtn">Fold</button>
    </div>
  </div>

  <script>
    const slider = document.getElementById('foldSlider');
    const playBtn = document.getElementById('playBtn');
    const openBtn = document.getElementById('openBtn');
    const foldBtn = document.getElementById('foldBtn');

    const heartRight = document.getElementById('heartRight');
    const aRight = document.getElementById('aRight');
    const heartBadge = document.getElementById('heartBadge');
    const aBadge = document.getElementById('aBadge');

    let angle = 0;
    let isPlaying = true;
    let animDir = 1; // 1 = folding, -1 = unfolding
    let pauseTimer = 0;
    let lastTime = performance.now();

    function updateVisuals(deg) {
      angle = deg;
      slider.value = deg;
      const rot = `rotateY(-${deg}deg)`;
      heartRight.style.transform = rot;
      aRight.style.transform = rot;

      const isFolded = deg >= 170;
      heartBadge.classList.toggle('visible', isFolded);
      aBadge.classList.toggle('visible', isFolded);
    }

    function animate(currentTime) {
      const dt = (currentTime - lastTime) / 1000;
      lastTime = currentTime;

      if (isPlaying) {
        if (pauseTimer > 0) {
          pauseTimer -= dt;
        } else {
          // Speed: ~75 degrees per sec (~2.4s for full fold)
          angle += animDir * 75 * dt;

          if (angle >= 180) {
            angle = 180;
            animDir = -1;
            pauseTimer = 1.4; // Pause to observe full match
          } else if (angle <= 0) {
            angle = 0;
            animDir = 1;
            pauseTimer = 1.0; // Pause at open state
          }
          updateVisuals(angle);
        }
      }
      requestAnimationFrame(animate);
    }

    requestAnimationFrame((t) => {
      lastTime = t;
      animate(t);
    });

    // Slider interaction
    slider.addEventListener('input', (e) => {
      isPlaying = false;
      playBtn.textContent = '▶ Auto';
      playBtn.classList.remove('active');
      updateVisuals(parseFloat(e.target.value));
    });

    // Auto Play Toggle
    playBtn.addEventListener('click', () => {
      isPlaying = !isPlaying;
      if (isPlaying) {
        playBtn.textContent = '⏸ Pause';
        playBtn.classList.add('active');
        lastTime = performance.now();
      } else {
        playBtn.textContent = '▶ Auto';
        playBtn.classList.remove('active');
      }
    });

    // Step to Open
    openBtn.addEventListener('click', () => {
      isPlaying = false;
      playBtn.textContent = '▶ Auto';
      playBtn.classList.remove('active');
      updateVisuals(0);
    });

    // Step to Fold
    foldBtn.addEventListener('click', () => {
      isPlaying = false;
      playBtn.textContent = '▶ Auto';
      playBtn.classList.remove('active');
      updateVisuals(180);
    });
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      background: transparent;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
      padding: 12px;
    }
    .grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 12px;
      width: 100%;
      max-width: 600px;
    }
    .tile {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 8px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      box-shadow: 0 1px 3px rgba(0,0,0,0.04);
      cursor: pointer;
      user-select: none;
      transition: transform 0.2s ease, box-shadow 0.2s ease;
    }
    .tile:active {
      transform: translateY(1px);
    }
    .svg-container {
      width: 100%;
      max-width: 120px;
      aspect-ratio: 1 / 1;
      position: relative;
    }
    svg {
      width: 100%;
      height: 100%;
      display: block;
      overflow: visible;
    }
    .label-title {
      font-size: 14px;
      font-weight: 700;
      text-align: center;
      margin-top: 8px;
      line-height: 1.2;
    }
    .label-sub {
      font-size: 12px;
      color: #6b7280;
      font-weight: 500;
      text-align: center;
      margin-top: 2px;
    }
    .purple-text { color: #7c3aed; }
    .teal-text { color: #0891b2; }
    .both-text { color: #2563eb; }

    .fold-half {
      transform-origin: 50px 50px;
      transition: transform 0.5s ease, opacity 0.5s ease;
    }
    .tile.folded .fold-v {
      transform: scaleX(-1);
      opacity: 0.7;
    }
    .tile.folded .fold-h {
      transform: scaleY(-1);
      opacity: 0.7;
    }
    .hint {
      font-size: 12px;
      color: #94a3b8;
      margin-top: 10px;
      text-align: center;
    }
  </style>
</head>
<body>

  <div class="grid">
    
    <div class="tile" id="tile1" onclick="toggleFold(1)">
      <div class="svg-container">
        <svg viewBox="0 0 100 100">
          
          <path d="M 20 80 L 20 24 L 50 62" fill="none" stroke="#1e2945" stroke-width="12" stroke-linecap="round" stroke-linejoin="round"/>
          
          <g class="fold-half fold-v">
            <path d="M 50 62 L 80 24 L 80 80" fill="none" stroke="#1e2945" stroke-width="12" stroke-linecap="round" stroke-linejoin="round"/>
          </g>
          
          <line x1="50" y1="8" x2="50" y2="92" stroke="#7c3aed" stroke-width="3" stroke-dasharray="6 4" stroke-linecap="round"/>
        </svg>
      </div>
      <div class="label-title purple-text">Vertical</div>
      <div class="label-sub">Up & Down</div>
    </div>

    
    <div class="tile" id="tile2" onclick="toggleFold(2)">
      <div class="svg-container">
        <svg viewBox="0 0 100 100">
          
          <path d="M 76 24 L 24 24 L 24 50 L 64 50" fill="none" stroke="#1e2945" stroke-width="12" stroke-linecap="round" stroke-linejoin="round"/>
          
          <g class="fold-half fold-h">
            <path d="M 24 50 L 24 76 L 76 76" fill="none" stroke="#1e2945" stroke-width="12" stroke-linecap="round" stroke-linejoin="round"/>
          </g>
          
          <line x1="8" y1="50" x2="92" y2="50" stroke="#0891b2" stroke-width="3" stroke-dasharray="6 4" stroke-linecap="round"/>
        </svg>
      </div>
      <div class="label-title teal-text">Horizontal</div>
      <div class="label-sub">Side to Side</div>
    </div>

    
    <div class="tile" id="tile3" onclick="toggleFold(3)">
      <div class="svg-container">
        <svg viewBox="0 0 100 100">
          
          <g class="fold-half fold-v">
            <line x1="50" y1="20" x2="50" y2="80" stroke="#1e2945" stroke-width="13" stroke-linecap="round"/>
            <line x1="20" y1="50" x2="80" y2="50" stroke="#1e2945" stroke-width="13" stroke-linecap="round"/>
          </g>
          
          <line x1="8" y1="50" x2="92" y2="50" stroke="#0891b2" stroke-width="3" stroke-dasharray="6 4" stroke-linecap="round"/>
          
          <line x1="50" y1="8" x2="50" y2="92" stroke="#7c3aed" stroke-width="3" stroke-dasharray="6 4" stroke-linecap="round"/>
        </svg>
      </div>
      <div class="label-title both-text">Both Directions</div>
      <div class="label-sub">2 Lines</div>
    </div>
  </div>

  <div class="hint">Tap a shape to fold along symmetry line</div>

  <script>
    function toggleFold(num) {
      const tile = document.getElementById('tile' + num);
      if (tile) {
        tile.classList.toggle('folded');
      }
    }
  </script>
</body>
</html>

Lines of Symmetry in Two-Dimensional Figures

Drawing Lines of Symmetry

Finding All Lines of Symmetry

Figures With No Lines of Symmetry

math

Lines of Symmetry

Propriétés de la symétrie axiale : pliage et conservation

Reconnaître si deux figures sont symétriques par rapport à une droite

Trouver les deux axes de symétrie du rectangle

Trouver les quatre axes de symétrie du carré

Axes de symétrie du losange et des triangles particuliers

Symétrie par rapport à un axe vertical sur papier quadrillé

Symétrie par rapport à un axe horizontal sur papier quadrillé

Compléter une figure à un ou deux axes de symétrie

Symétrique d'une figure qui coupe l'axe de symétrie

La symétrie axiale : reconnaissance, axes et constructions

Propriétés de la symétrie axiale : longueurs, angles et formes

Symétrie par rapport à une diagonale du quadrillage

La symétrie axiale sur quadrillage

Shapes With More Than One Line of Symmetry

Completing Symmetrical Figures Across a Vertical Mirror Line

Completing Symmetrical Figures Across a Horizontal Mirror Line

Completing Symmetrical Figures Across Diagonal Mirror Lines

Understanding Rotational Symmetry and Order of Rotation

Describing Translations That Move Points Between Coordinates

Rigid Plane Motions: Translations, Reflections, and Rotations

Lines of Symmetry, Rotational Symmetry, and Transformations

Définition du symétrique d'un point par rapport à une droite

Construire le symétrique d'un point à l'équerre et au compas

Construire le symétrique d'un point au compas seul

Symétrique d'une droite et conservation de l'alignement

Conservation des angles et symétrique d'un angle

Symétrique d'un cercle et conservation des aires

Construire le symétrique d'une figure complexe sur papier uni

Démontrer des propriétés géométriques grâce à la symétrie axiale

Symétrie axiale : définition, propriétés et constructions

认识生活中的平移现象

平移的特征：形状、大小和方向不变，位置改变

数出图形平移的格数：关键对应点分析法

在方格纸上画出沿水平或竖直方向平移后的图形

在方格纸上画出连续平移（先横后竖）后的图形

图形的运动：平移的认识与画法

Finding Line Symmetry in Shapes

Finding Rotational Symmetry in Shapes

Creating Symmetrical Patterns

Drawing Symmetrical Pictures

Symmetry in the Environment

Line and Rotational Symmetry

认识生活中的旋转现象

旋转的三要素：旋转中心、旋转方向（顺时针/逆时针）与旋转角度

OGM.5.G.4

Aligned learning resources

Related diagrams