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

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #f8fafc;
      color: #1e293b;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
      padding: 12px;
    }

    .main-wrapper {
      width: 100%;
      max-width: 520px;
      display: flex;
      flex-direction: column;
      align-items: center;
    }

    .tabs {
      display: flex;
      gap: 10px;
      margin-bottom: 14px;
    }

    .tab-btn {
      padding: 8px 18px;
      font-size: 14px;
      font-weight: 700;
      border: 2px solid #cbd5e1;
      background: #ffffff;
      color: #475569;
      border-radius: 20px;
      cursor: pointer;
      transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
    }

    .tab-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }

    .tab-btn.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
    }

    .scene-view {
      width: 100%;
      display: flex;
      flex-direction: column;
      align-items: center;
    }

    .svg-container {
      width: 100%;
      max-width: 460px;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
    }

    .result-badge {
      margin-top: 14px;
      background: #eff6ff;
      border: 2px solid #3b82f6;
      border-radius: 12px;
      padding: 10px 16px;
      text-align: center;
      width: 100%;
      max-width: 440px;
    }

    .result-title {
      font-size: 15px;
      font-weight: 800;
      color: #1d4ed8;
      line-height: 1.35;
    }

    .result-sub {
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      margin-top: 4px;
    }

    .spill-anim {
      animation: gentleDrip 2.4s infinite ease-in-out;
    }

    @keyframes gentleDrip {
      0%, 100% {
        opacity: 0.85;
        transform: translateY(0);
      }
      50% {
        opacity: 1;
        transform: translateY(2px);
      }
    }

    @media (max-width: 400px) {
      .result-title {
        font-size: 13.5px;
      }
      .result-sub {
        font-size: 11px;
      }
      .tab-btn {
        padding: 6px 14px;
        font-size: 13px;
      }
    }
  </style>
</head>
<body>

  <div class="main-wrapper">
    
    <div class="tabs" role="tablist" aria-label="Capacity comparison examples">
      <button class="tab-btn active" id="tab1" onclick="showScene(1)" role="tab" aria-selected="true">Example 1: Mug & Cup</button>
      <button class="tab-btn" id="tab2" onclick="showScene(2)" role="tab" aria-selected="false">Example 2: Bowl & Cup</button>
    </div>

    
    <div class="scene-view" id="scene1">
      <div class="svg-container">
        <svg viewBox="0 0 380 205" aria-label="Yellow Mug pouring water into small Red Cup causing it to overflow">
          
          <rect x="25" y="172" width="330" height="14" rx="7" fill="#cbd5e1"/>
          
          <ellipse cx="225" cy="174" rx="65" ry="6" fill="#38bdf8" opacity="0.85"/>

          
          <rect x="24" y="15" width="96" height="24" rx="12" fill="#fef08a" stroke="#ca8a04" stroke-width="1.5"/>
          <text x="72" y="31" text-anchor="middle" font-size="12" font-weight="bold" fill="#854d0e">Yellow Mug</text>

          
          <path d="M 105 68 C 145 70, 192 78, 218 98" fill="none" stroke="#38bdf8" stroke-width="8" stroke-linecap="round"/>

          
          <g transform="translate(65, 40) rotate(35)">
            
            <path d="M -10 15 C -24 15, -24 45, -10 45" fill="none" stroke="#ca8a04" stroke-width="4" stroke-linecap="round"/>
            
            <rect x="0" y="0" width="50" height="60" rx="6" fill="#facc15" stroke="#ca8a04" stroke-width="3"/>
            
            <rect x="3" y="10" width="44" height="46" rx="3" fill="#38bdf8"/>
          </g>

          
          <g transform="translate(195, 95)">
            
            <polygon points="4,2 46,2 39,68 11,68" fill="#38bdf8"/>
            
            
            <polygon points="0,0 50,0 42,70 8,70" fill="none" stroke="#dc2626" stroke-width="3.5" stroke-linejoin="round"/>
            
            
            <ellipse cx="25" cy="1" rx="25" ry="5" fill="#60a5fa"/>

            
            <g class="spill-anim">
              <path d="M 0 3 Q -6 18, -3 38 Q -7 55, -4 72" fill="none" stroke="#38bdf8" stroke-width="4" stroke-linecap="round"/>
              <path d="M 50 3 Q 56 18, 53 38 Q 57 55, 54 72" fill="none" stroke="#38bdf8" stroke-width="4" stroke-linecap="round"/>
            </g>

            
            <path d="M 54 6 Q 64 16, 61 32" fill="none" stroke="#ef4444" stroke-width="2.5" stroke-dasharray="3 3"/>
            <polygon points="61,37 56,29 65,30" fill="#ef4444"/>
          </g>

          
          <rect x="270" y="65" width="86" height="24" rx="12" fill="#fee2e2" stroke="#dc2626" stroke-width="1.5"/>
          <text x="313" y="81" text-anchor="middle" font-size="12" font-weight="bold" fill="#991b1b">Red Cup</text>
          
          
          <rect x="264" y="105" width="98" height="24" rx="12" fill="#fef2f2" stroke="#ef4444" stroke-width="1.5"/>
          <text x="313" y="121" text-anchor="middle" font-size="11" font-weight="bold" fill="#dc2626">💧 Spilling over!</text>
        </svg>
      </div>

      <div class="result-badge">
        <div class="result-title">Yellow Mug holds MORE because Red Cup overflows!</div>
        <div class="result-sub">When liquid spills over, the pouring container has a larger capacity.</div>
      </div>
    </div>

    
    <div class="scene-view" id="scene2" style="display: none;">
      <div class="svg-container">
        <svg viewBox="0 0 380 205" aria-label="Big Green Bowl pouring water into Purple Cup causing it to overflow">
          
          <rect x="25" y="172" width="330" height="14" rx="7" fill="#cbd5e1"/>
          
          <ellipse cx="225" cy="174" rx="65" ry="6" fill="#38bdf8" opacity="0.85"/>

          
          <rect x="20" y="15" width="102" height="24" rx="12" fill="#dcfce7" stroke="#16a34a" stroke-width="1.5"/>
          <text x="71" y="31" text-anchor="middle" font-size="12" font-weight="bold" fill="#15803d">Green Bowl</text>

          
          <path d="M 112 68 C 148 70, 192 78, 218 98" fill="none" stroke="#38bdf8" stroke-width="8" stroke-linecap="round"/>

          
          <g transform="translate(62, 40) rotate(35)">
            
            <path d="M 0 10 Q 32 60, 65 10 Z" fill="#22c55e" stroke="#15803d" stroke-width="3"/>
            
            <path d="M 5 12 Q 32 50, 60 12 Z" fill="#38bdf8"/>
          </g>

          
          <g transform="translate(198, 95)">
            
            <rect x="4" y="2" width="36" height="66" rx="2" fill="#38bdf8"/>
            
            
            <rect x="0" y="0" width="44" height="70" rx="4" fill="none" stroke="#9333ea" stroke-width="3.5"/>
            
            
            <ellipse cx="22" cy="1" rx="22" ry="5" fill="#60a5fa"/>

            
            <g class="spill-anim">
              <path d="M 0 3 Q -6 18, -3 38 Q -7 55, -4 72" fill="none" stroke="#38bdf8" stroke-width="4" stroke-linecap="round"/>
              <path d="M 44 3 Q 50 18, 47 38 Q 51 55, 48 72" fill="none" stroke="#38bdf8" stroke-width="4" stroke-linecap="round"/>
            </g>

            
            <path d="M 48 6 Q 58 16, 55 32" fill="none" stroke="#9333ea" stroke-width="2.5" stroke-dasharray="3 3"/>
            <polygon points="55,37 50,29 59,30" fill="#9333ea"/>
          </g>

          
          <rect x="270" y="65" width="90" height="24" rx="12" fill="#f3e8ff" stroke="#9333ea" stroke-width="1.5"/>
          <text x="315" y="81" text-anchor="middle" font-size="12" font-weight="bold" fill="#6b21a8">Purple Cup</text>
          
          
          <rect x="264" y="105" width="98" height="24" rx="12" fill="#faf5ff" stroke="#9333ea" stroke-width="1.5"/>
          <text x="313" y="121" text-anchor="middle" font-size="11" font-weight="bold" fill="#7e22ce">💧 Spilling over!</text>
        </svg>
      </div>

      <div class="result-badge">
        <div class="result-title">Green Bowl holds MORE because Purple Cup overflows!</div>
        <div class="result-sub">When liquid spills over, the pouring container has a larger capacity.</div>
      </div>
    </div>
  </div>

  <script>
    function showScene(num) {
      const scene1 = document.getElementById('scene1');
      const scene2 = document.getElementById('scene2');
      const tab1 = document.getElementById('tab1');
      const tab2 = document.getElementById('tab2');

      if (num === 1) {
        scene1.style.display = 'flex';
        scene2.style.display = 'none';
        tab1.classList.add('active');
        tab2.classList.remove('active');
        tab1.setAttribute('aria-selected', 'true');
        tab2.setAttribute('aria-selected', 'false');
      } else {
        scene1.style.display = 'none';
        scene2.style.display = 'flex';
        tab1.classList.remove('active');
        tab2.classList.add('active');
        tab1.setAttribute('aria-selected', 'false');
        tab2.setAttribute('aria-selected', 'true');
      }
    }
  </script>
</body>
</html>

Comparing Capacity Directly: Holding More or Less

<!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;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      user-select: none;
    }

    body {
      width: 100%;
      background: #f8fafc;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 16px 12px;
      min-height: 100%;
    }

    .main-stage {
      width: 100%;
      max-width: 520px;
      display: flex;
      align-items: flex-end;
      justify-content: space-around;
      gap: 12px;
      position: relative;
      margin-top: 10px;
      padding-bottom: 8px;
    }

    /* Floor line */
    .floor {
      position: absolute;
      bottom: 0;
      left: 4%;
      width: 92%;
      height: 4px;
      background: #e2e8f0;
      border-radius: 2px;
      z-index: 1;
    }

    /* Container columns */
    .item-col {
      display: flex;
      flex-direction: column;
      align-items: center;
      z-index: 2;
      position: relative;
    }

    /* Small Cup */
    .cup-wrap {
      width: 70px;
      height: 90px;
      border: 4px solid #0284c7;
      border-top: none;
      border-radius: 0 0 10px 10px;
      background: #ffffff;
      position: relative;
      overflow: hidden;
      display: flex;
      align-items: flex-end;
    }

    .cup-water {
      width: 100%;
      height: 0%;
      background: #38bdf8;
      transition: height 0.6s ease;
    }

    .cup-water.filled {
      height: 85%;
    }

    /* Orange Tub */
    .tub-wrap {
      width: 150px;
      height: 140px;
      border: 5px solid #ea580c;
      border-top: none;
      border-radius: 0 0 16px 16px;
      background: #fff7ed;
      position: relative;
      display: flex;
      flex-direction: column;
      justify-content: flex-end;
    }

    .tub-water {
      width: 100%;
      height: 32px;
      background: #38bdf8;
      border-top: 3px solid #0284c7;
      border-radius: 0 0 11px 11px;
      transition: height 0.6s ease;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 13px;
      font-weight: 700;
      color: #0369a1;
    }

    /* Dashed Empty Space zone */
    .empty-space {
      flex: 1;
      margin: 6px 6px 4px 6px;
      border: 2px dashed #f97316;
      border-radius: 6px;
      background: rgba(254, 215, 170, 0.35);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 2px;
      position: relative;
    }

    .empty-badge {
      font-size: 12px;
      font-weight: 800;
      color: #c2410c;
      background: #ffedd5;
      padding: 3px 8px;
      border-radius: 12px;
      border: 1px solid #fed7aa;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    /* Arrow between */
    .pour-arrow {
      font-size: 24px;
      color: #0284c7;
      margin-bottom: 45px;
      z-index: 2;
      display: flex;
      flex-direction: column;
      align-items: center;
      font-weight: 700;
    }

    .pour-label {
      font-size: 12px;
      color: #0284c7;
      font-weight: 700;
      margin-top: -4px;
    }

    /* Item text labels */
    .item-title {
      font-size: 14px;
      font-weight: 700;
      margin-top: 8px;
      text-align: center;
    }

    .item-sub {
      font-size: 13px;
      font-weight: 800;
      padding: 2px 8px;
      border-radius: 6px;
      margin-top: 4px;
    }

    .sub-less {
      color: #0369a1;
      background: #e0f2fe;
    }

    .sub-more {
      color: #c2410c;
      background: #ffedd5;
    }

    /* Main Lesson Text Badge */
    .summary-badge {
      width: 100%;
      max-width: 520px;
      background: #ffffff;
      border: 2px solid #bae6fd;
      border-left: 6px solid #0284c7;
      border-radius: 10px;
      padding: 10px 14px;
      font-size: 15px;
      line-height: 1.4;
      color: #0f172a;
      text-align: center;
      box-shadow: 0 2px 6px rgba(0,0,0,0.04);
      margin-top: 14px;
    }

    .summary-badge strong.less {
      color: #0284c7;
    }

    .summary-badge strong.more {
      color: #ea580c;
    }

    /* Interactive controls */
    .controls {
      display: flex;
      gap: 8px;
      margin-top: 12px;
    }

    .btn {
      border: none;
      background: #e2e8f0;
      color: #334155;
      font-size: 13px;
      font-weight: 700;
      padding: 6px 14px;
      border-radius: 20px;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      box-shadow: 0 1px 3px rgba(0,0,0,0.06);
    }

    .btn.active {
      background: #0284c7;
      color: #ffffff;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="btn" id="btnBefore" onclick="setStep('before')">1. Full Cup</button>
    <button class="btn active" id="btnAfter" onclick="setStep('after')">2. Poured into Tub</button>
  </div>

  
  <div class="main-stage">
    <div class="floor"></div>

    
    <div class="item-col">
      <div class="cup-wrap" id="cup">
        <div class="cup-water" id="cupWater"></div>
      </div>
      <div class="item-title">Small Cup</div>
      <div class="item-sub sub-less">Holds LESS</div>
    </div>

    
    <div class="pour-arrow" id="arrow">
      <span>➔</span>
      <span class="pour-label">Poured In</span>
    </div>

    
    <div class="item-col">
      <div class="tub-wrap" id="tub">
        <div class="empty-space" id="emptySpace">
          <div class="empty-badge">Empty Space</div>
          <span style="font-size: 11px; font-weight: 700; color: #ea580c;">(Extra Room)</span>
        </div>
        <div class="tub-water" id="tubWater">All the water!</div>
      </div>
      <div class="item-title">Orange Tub</div>
      <div class="item-sub sub-more">Holds MORE</div>
    </div>
  </div>

  
  <div class="summary-badge">
    <strong class="less">Small Cup</strong> holds <strong>LESS</strong>.
    <strong class="more">Orange Tub</strong> holds <strong>MORE</strong> (it has extra room!).
  </div>

  <script>
    function setStep(step) {
      const btnBefore = document.getElementById('btnBefore');
      const btnAfter = document.getElementById('btnAfter');
      const cupWater = document.getElementById('cupWater');
      const tubWater = document.getElementById('tubWater');
      const emptySpace = document.getElementById('emptySpace');
      const arrow = document.getElementById('arrow');

      if (step === 'before') {
        btnBefore.classList.add('active');
        btnAfter.classList.remove('active');
        cupWater.classList.add('filled');
        tubWater.style.height = '0px';
        tubWater.style.borderTop = 'none';
        tubWater.textContent = '';
        emptySpace.style.opacity = '0.3';
        arrow.style.opacity = '0.3';
      } else {
        btnAfter.classList.add('active');
        btnBefore.classList.remove('active');
        cupWater.classList.remove('filled');
        tubWater.style.height = '32px';
        tubWater.style.borderTop = '3px solid #0284c7';
        tubWater.textContent = 'All the water!';
        emptySpace.style.opacity = '1';
        arrow.style.opacity = '1';
      }
    }

    // Default state: after pour
    setStep('after');
  </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">
  <script src="{{VENDOR_CDN}}/classace-diagram.js"></script>
  <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;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 6px 10px;
      user-select: none;
      min-height: 100vh;
    }

    .header {
      text-align: center;
      margin-bottom: 4px;
    }
    .badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #e0f2fe;
      color: #0369a1;
      padding: 3px 12px;
      border-radius: 20px;
      font-size: 12px;
      font-weight: 700;
      letter-spacing: 0.5px;
      text-transform: uppercase;
    }

    .stage {
      position: relative;
      width: 100%;
      max-width: 440px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .scene-svg {
      width: 100%;
      height: auto;
      display: block;
    }

    /* Animated elements */
    .mug-group {
      transition: transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
      transform-origin: 160px 140px;
    }
    .water-mug {
      transition: height 0.8s ease, y 0.8s ease;
    }
    .water-jar {
      transition: height 0.8s ease, y 0.8s ease;
    }
    .stream {
      opacity: 0;
      transition: opacity 0.3s ease;
    }
    .star {
      opacity: 0;
      transition: opacity 0.5s ease;
    }

    /* Result Banner */
    .banner {
      position: absolute;
      bottom: 24px;
      left: 50%;
      transform: translateX(-50%) translateY(10px);
      opacity: 0;
      background: linear-gradient(135deg, #10b981, #059669);
      color: #ffffff;
      padding: 6px 14px;
      border-radius: 20px;
      font-size: 12px;
      font-weight: 700;
      box-shadow: 0 4px 12px rgba(16, 185, 129, 0.4);
      transition: opacity 0.4s ease, transform 0.4s ease;
      white-space: nowrap;
      display: flex;
      align-items: center;
      gap: 5px;
      pointer-events: none;
      max-width: 92%;
      text-align: center;
    }

    @media (max-width: 380px) {
      .banner {
        font-size: 11px;
        padding: 5px 10px;
        bottom: 20px;
      }
    }

    /* Controls */
    .controls {
      display: flex;
      align-items: center;
      gap: 8px;
      margin-top: 2px;
    }
    .btn {
      border: none;
      background: #f1f5f9;
      color: #334155;
      padding: 6px 14px;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: background-color 0.2s, opacity 0.2s;
    }
    .btn:hover {
      opacity: 0.9;
    }
    .btn:active {
      background: #e2e8f0;
    }
    .btn-primary {
      background: #0284c7;
      color: #ffffff;
    }
    .btn-primary:active {
      background: #0369a1;
    }

    .step-dots {
      display: flex;
      gap: 6px;
      align-items: center;
      margin: 0 4px;
    }
    .dot {
      width: 9px;
      height: 9px;
      border-radius: 50%;
      background: #cbd5e1;
      cursor: pointer;
      transition: background-color 0.2s ease;
    }
    .dot.active {
      background: #0284c7;
    }
  </style>
</head>
<body>

  <div class="header">
    <div class="badge">Comparing Capacity Directly</div>
  </div>

  <div class="stage">
    <svg class="scene-svg" viewBox="0 0 440 225">
      <defs>
        
        <linearGradient id="waterGrad" x1="0%" y1="0%" x2="0%" y2="100%">
          <stop offset="0%" stop-color="#38bdf8" />
          <stop offset="100%" stop-color="#0284c7" />
        </linearGradient>

        <linearGradient id="mugGrad" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#10b981" />
          <stop offset="100%" stop-color="#059669" />
        </linearGradient>

        
        <clipPath id="mugClip">
          <rect x="75" y="80" width="70" height="90" rx="8" />
        </clipPath>

        
        <clipPath id="jarClip">
          <rect x="275" y="80" width="70" height="90" rx="10" />
        </clipPath>
      </defs>

      
      <line x1="30" y1="180" x2="410" y2="180" stroke="#cbd5e1" stroke-width="3" stroke-linecap="round" />

      
      <path id="pourStream" class="stream" d="M 175 105 Q 230 110 305 130" fill="none" stroke="#38bdf8" stroke-width="8" stroke-linecap="round" stroke-dasharray="8,4" />

      
      <g id="mugGroup" class="mug-group">
        
        <path d="M 75 100 C 45 100, 45 150, 75 150" fill="none" stroke="#059669" stroke-width="8" stroke-linecap="round" />
        
        
        <rect x="75" y="80" width="70" height="90" rx="8" fill="#e2e8f0" stroke="#059669" stroke-width="3" />
        
        
        <g clip-path="url(#mugClip)">
          <rect id="mugWater" class="water-mug" x="75" y="86" width="70" height="84" fill="url(#waterGrad)" />
        </g>

        
        <ellipse cx="110" cy="80" rx="35" ry="6" fill="#10b981" stroke="#047857" stroke-width="2" />
        
        
        <text id="mugLabel" x="110" y="202" text-anchor="middle" font-size="13" font-weight="700" fill="#047857">Green Mug</text>
      </g>

      
      <g id="jarGroup">
        
        <rect x="275" y="80" width="70" height="90" rx="10" fill="#f1f5f9" stroke="#2563eb" stroke-width="3" />
        
        
        <rect x="285" y="72" width="50" height="8" rx="2" fill="#bfdbfe" stroke="#2563eb" stroke-width="2" />
        
        
        <g clip-path="url(#jarClip)">
          <rect id="jarWater" class="water-jar" x="275" y="170" width="70" height="0" fill="url(#waterGrad)" />
        </g>

        
        <line x1="275" y1="80" x2="345" y2="80" stroke="#38bdf8" stroke-width="1.5" stroke-dasharray="3,3" />

        
        <text x="310" y="202" text-anchor="middle" font-size="13" font-weight="700" fill="#1d4ed8">Blue Jar</text>
      </g>

      
      <g id="starsGroup">
        <text class="star" id="star1" x="245" y="78" font-size="20" fill="#eab308">✦</text>
        <text class="star" id="star2" x="355" y="72" font-size="24" fill="#f59e0b">★</text>
        <text class="star" id="star3" x="365" y="130" font-size="18" fill="#eab308">✦</text>
        <text class="star" id="star4" x="240" y="145" font-size="16" fill="#fbbf24">★</text>
      </g>
    </svg>

    
    <div id="banner" class="banner">
      <span>✦</span>
      <span>Exact Fit! Both containers have equal capacity.</span>
      <span>✦</span>
    </div>
  </div>

  <div class="controls">
    <button class="btn" id="prevBtn">◀ Back</button>
    <div class="step-dots">
      <div class="dot active" data-step="0"></div>
      <div class="dot" data-step="1"></div>
      <div class="dot" data-step="2"></div>
    </div>
    <button class="btn btn-primary" id="nextBtn">Pour ▶</button>
  </div>

  <script>
    const steps = [
      {
        mugTransform: 'rotate(0) translate(0, 0)',
        mugWater: { y: 86, height: 84 },
        jarWater: { y: 170, height: 0 },
        stream: 0,
        stars: 0,
        banner: false,
        nextText: 'Pour ▶'
      },
      {
        mugTransform: 'rotate(42deg) translate(80px, -70px)',
        mugWater: { y: 125, height: 45 },
        jarWater: { y: 125, height: 45 },
        stream: 1,
        stars: 0,
        banner: false,
        nextText: 'Full Fit ▶'
      },
      {
        mugTransform: 'rotate(0) translate(0, 0)',
        mugWater: { y: 170, height: 0 },
        jarWater: { y: 80, height: 90 },
        stream: 0,
        stars: 1,
        banner: true,
        nextText: 'Reset ↺'
      }
    ];

    let currentStep = 0;

    const mugGroup = document.getElementById('mugGroup');
    const mugWater = document.getElementById('mugWater');
    const jarWater = document.getElementById('jarWater');
    const pourStream = document.getElementById('pourStream');
    const banner = document.getElementById('banner');
    const stars = document.querySelectorAll('.star');
    const dots = document.querySelectorAll('.dot');
    const prevBtn = document.getElementById('prevBtn');
    const nextBtn = document.getElementById('nextBtn');

    function applyStep(idx) {
      currentStep = idx;
      const s = steps[idx];

      mugGroup.style.transform = s.mugTransform;
      mugWater.setAttribute('y', s.mugWater.y);
      mugWater.setAttribute('height', s.mugWater.height);

      jarWater.setAttribute('y', s.jarWater.y);
      jarWater.setAttribute('height', s.jarWater.height);

      pourStream.style.opacity = s.stream;

      stars.forEach(star => {
        star.style.opacity = s.stars;
      });

      if (s.banner) {
        banner.style.opacity = '1';
        banner.style.transform = 'translateX(-50%) translateY(0)';
      } else {
        banner.style.opacity = '0';
        banner.style.transform = 'translateX(-50%) translateY(10px)';
      }

      dots.forEach((dot, i) => {
        dot.classList.toggle('active', i === idx);
      });

      nextBtn.textContent = s.nextText;
      prevBtn.style.visibility = idx === 0 ? 'hidden' : 'visible';
    }

    prevBtn.addEventListener('click', () => {
      if (currentStep > 0) {
        applyStep(currentStep - 1);
      }
    });

    nextBtn.addEventListener('click', () => {
      if (currentStep < steps.length - 1) {
        applyStep(currentStep + 1);
      } else {
        applyStep(0);
      }
    });

    dots.forEach((dot, i) => {
      dot.addEventListener('click', () => applyStep(i));
    });

    let timer = null;
    function autoPlay() {
      timer = setInterval(() => {
        if (currentStep < steps.length - 1) {
          applyStep(currentStep + 1);
        } else {
          clearInterval(timer);
          setTimeout(() => {
            applyStep(0);
            autoPlay();
          }, 3500);
        }
      }, 2600);
    }

    const stopAuto = () => {
      if (timer) clearInterval(timer);
    };
    prevBtn.addEventListener('click', stopAuto);
    nextBtn.addEventListener('click', stopAuto);
    dots.forEach(d => d.addEventListener('click', stopAuto));

    applyStep(0);
    autoPlay();
  </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: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 12px;
      user-select: none;
    }

    /* Tip Badge */
    .tip-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #eff6ff;
      border: 1.5px solid #60a5fa;
      color: #1d4ed8;
      font-size: 14px;
      font-weight: 700;
      padding: 6px 14px;
      border-radius: 20px;
      box-shadow: 0 0 10px rgba(96, 165, 250, 0.35);
    }

    /* Main Stage */
    .stage {
      width: 100%;
      max-width: 520px;
      height: 250px;
      position: relative;
    }

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

    /* Water Animations */
    .water-tall {
      transition: y 0.9s ease, height 0.9s ease;
    }
    .water-bowl {
      transition: y 0.9s ease, height 0.9s ease;
    }
    .pour-stream {
      opacity: 0;
      transition: opacity 0.25s ease;
    }
    .pour-stream.active {
      opacity: 1;
    }

    /* Annotations */
    .annotation {
      transition: opacity 0.4s ease;
    }

    /* Controls & Banner */
    .controls {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
      width: 100%;
      max-width: 480px;
    }

    .btn-group {
      display: flex;
      gap: 8px;
    }

    .btn {
      appearance: none;
      border: 1.5px solid #cbd5e1;
      background: #f8fafc;
      color: #334155;
      font-size: 14px;
      font-weight: 700;
      padding: 8px 16px;
      border-radius: 999px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background 0.15s, border-color 0.15s, color 0.15s;
    }
    .btn:hover {
      background: #e2e8f0;
    }
    .btn.active {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
    }

    .result-pill {
      font-size: 14px;
      font-weight: 800;
      color: #0369a1;
      background: #e0f2fe;
      padding: 6px 14px;
      border-radius: 12px;
      border: 1px solid #bae6fd;
      text-align: center;
    }
  </style>
</head>
<body>

  
  <div class="tip-badge">
    <span>🔍</span> Do not be fooled by height!
  </div>

  
  <div class="stage">
    <svg viewBox="0 0 520 250">
      <defs>
        
        <linearGradient id="waterGrad" x1="0" y1="0" x2="0" y2="1">
          <stop offset="0%" stop-color="#38bdf8" />
          <stop offset="100%" stop-color="#0284c7" />
        </linearGradient>
        <linearGradient id="glassGrad" x1="0" y1="0" x2="1" y2="0">
          <stop offset="0%" stop-color="rgba(255,255,255,0.7)" />
          <stop offset="20%" stop-color="rgba(255,255,255,0.2)" />
          <stop offset="80%" stop-color="rgba(255,255,255,0.1)" />
          <stop offset="100%" stop-color="rgba(255,255,255,0.5)" />
        </linearGradient>
        <clipPath id="tallClip">
          <rect x="70" y="30" width="56" height="170" rx="8" />
        </clipPath>
        <clipPath id="bowlClip">
          <rect x="250" y="100" width="190" height="100" rx="14" />
        </clipPath>
        <marker id="arrow" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1 L 8 5 L 0 9 z" fill="#ea580c" />
        </marker>
      </defs>

      
      <line x1="30" y1="202" x2="490" y2="202" stroke="#cbd5e1" stroke-width="3" stroke-linecap="round" />

      
      <g id="tallVaseGroup">
        
        <rect id="tallWater" class="water-tall" x="70" y="35" width="56" height="165" fill="url(#waterGrad)" clip-path="url(#tallClip)" />
        
        
        <rect x="70" y="30" width="56" height="170" rx="8" fill="url(#glassGrad)" stroke="#64748b" stroke-width="3" />
        <ellipse cx="98" cy="32" rx="26" ry="6" fill="#f8fafc" stroke="#64748b" stroke-width="2" />
        
        
        <text x="98" y="222" text-anchor="middle" font-size="14" font-weight="700" fill="#334155">Tall Vase</text>
        <text id="tallStateLabel" x="98" y="238" text-anchor="middle" font-size="12" font-weight="600" fill="#0284c7">FULL</text>
      </g>

      
      <path id="pourStream" class="pour-stream" d="M 126 40 Q 220 20, 310 140" fill="none" stroke="#38bdf8" stroke-width="7" stroke-linecap="round" stroke-dasharray="10 6" />

      
      <g id="bowlGroup">
        
        <rect id="bowlWater" class="water-bowl" x="250" y="200" width="190" height="0" fill="url(#waterGrad)" clip-path="url(#bowlClip)" />
        
        
        <rect x="250" y="100" width="190" height="100" rx="14" fill="url(#glassGrad)" stroke="#64748b" stroke-width="3" />
        <ellipse cx="345" cy="102" rx="93" ry="10" fill="#f8fafc" stroke="#64748b" stroke-width="2" />

        
        <line x1="250" y1="165" x2="440" y2="165" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="4 4" />

        
        <text x="345" y="222" text-anchor="middle" font-size="14" font-weight="700" fill="#334155">Wide Bowl</text>
        <text id="bowlStateLabel" x="345" y="238" text-anchor="middle" font-size="12" font-weight="600" fill="#64748b">EMPTY</text>
      </g>

      
      <g id="gapAnnotation" class="annotation" opacity="0">
        
        <path d="M 452 104 L 460 104 L 460 133 L 466 133 L 460 133 L 460 162 L 452 162" fill="none" stroke="#ea580c" stroke-width="2.5" />
        
        <text x="472" y="128" font-size="12" font-weight="800" fill="#ea580c">2/3 Still</text>
        <text x="472" y="143" font-size="12" font-weight="800" fill="#ea580c">Empty!</text>
        
        <line x1="390" y1="72" x2="355" y2="125" stroke="#ea580c" stroke-width="2" marker-end="url(#arrow)" />
        <rect x="330" y="50" width="125" height="22" rx="6" fill="#fff7ed" stroke="#fdba74" stroke-width="1" />
        <text x="392" y="65" text-anchor="middle" font-size="11" font-weight="700" fill="#c2410c">Lots of room left!</text>
      </g>
    </svg>
  </div>

  
  <div class="controls">
    <div class="btn-group">
      <button id="btn1" class="btn active" onclick="setStep(1)">1. Vase Full</button>
      <button id="btn2" class="btn" onclick="setStep(2)">2. Pour into Bowl 🫗</button>
    </div>
    <div class="result-pill">
      The Short Wide Bowl holds MORE capacity!
    </div>
  </div>

  <script>
    let currentStep = 1;
    let autoTimer = null;

    const tallWater = document.getElementById('tallWater');
    const bowlWater = document.getElementById('bowlWater');
    const pourStream = document.getElementById('pourStream');
    const gapAnnotation = document.getElementById('gapAnnotation');
    const tallState = document.getElementById('tallStateLabel');
    const bowlState = document.getElementById('bowlStateLabel');
    const btn1 = document.getElementById('btn1');
    const btn2 = document.getElementById('btn2');

    function setStep(step) {
      currentStep = step;
      if (step === 1) {
        // Reset to Step 1: Tall Full, Bowl Empty
        pourStream.classList.remove('active');
        tallWater.setAttribute('y', '35');
        tallWater.setAttribute('height', '165');
        bowlWater.setAttribute('y', '200');
        bowlWater.setAttribute('height', '0');
        gapAnnotation.style.opacity = '0';
        tallState.textContent = 'FULL';
        tallState.setAttribute('fill', '#0284c7');
        bowlState.textContent = 'EMPTY';
        bowlState.setAttribute('fill', '#64748b');

        btn1.classList.add('active');
        btn2.classList.remove('active');
      } else {
        // Step 2: Pour animation
        pourStream.classList.add('active');
        tallWater.setAttribute('y', '198');
        tallWater.setAttribute('height', '2');
        bowlWater.setAttribute('y', '165');
        bowlWater.setAttribute('height', '35');
        
        tallState.textContent = 'EMPTY';
        tallState.setAttribute('fill', '#64748b');
        bowlState.textContent = 'ONLY 1/3 FULL';
        bowlState.setAttribute('fill', '#0284c7');

        setTimeout(() => {
          pourStream.classList.remove('active');
          gapAnnotation.style.opacity = '1';
        }, 800);

        btn2.classList.add('active');
        btn1.classList.remove('active');
      }
    }

    // Auto-advance loop gently every 4.5 seconds so learners can watch if untouched
    function startAutoCycle() {
      autoTimer = setInterval(() => {
        setStep(currentStep === 1 ? 2 : 1);
      }, 4500);
    }

    // Pause auto timer when user clicks
    document.querySelectorAll('.btn').forEach(btn => {
      btn.addEventListener('click', () => {
        clearInterval(autoTimer);
      });
    });

    startAutoCycle();
  </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;
      color: #1e2945;
      background: #ffffff;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      user-select: none;
    }

    /* Top pouring stage */
    .stage {
      width: 100%;
      max-width: 480px;
      height: 150px;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
    }

    .cup-label {
      font-size: 14px;
      font-weight: 700;
      fill: #1e2945;
    }

    /* Animated water stream */
    .stream {
      stroke: #22b7ff;
      stroke-width: 6;
      stroke-linecap: round;
      stroke-dasharray: 8 6;
      animation: flow 0.8s linear infinite;
    }

    @keyframes flow {
      from { stroke-dashoffset: 28; }
      to { stroke-dashoffset: 0; }
    }

    /* Results section */
    .results-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 8px;
      width: 100%;
      max-width: 540px;
      margin-top: 8px;
    }

    .result-card {
      background: #f8fafc;
      border: 2px solid #e2e8f0;
      border-radius: 12px;
      padding: 8px 4px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      cursor: pointer;
      transition: border-color 0.25s ease, background-color 0.25s ease, box-shadow 0.25s ease;
    }

    .result-card.active {
      background: #ffffff;
      border-color: #22b7ff;
      box-shadow: 0 4px 12px rgba(34, 183, 255, 0.2);
    }

    .result-svg {
      width: 100%;
      height: 95px;
    }

    .card-title {
      font-size: 14px;
      font-weight: 800;
      margin-top: 6px;
      color: #1e2945;
      line-height: 1.2;
    }

    .card-sub {
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      margin-top: 2px;
    }

    /* Splash droplets animation */
    .splash {
      animation: pulse-splash 1.2s ease-in-out infinite alternate;
    }
    @keyframes pulse-splash {
      0% { opacity: 0.4; transform: translateY(0); }
      100% { opacity: 1; transform: translateY(-2px); }
    }

    /* Gap highlight */
    .gap-arrow {
      animation: bounce-gap 1s ease-in-out infinite alternate;
    }
    @keyframes bounce-gap {
      0% { transform: translateY(0); }
      100% { transform: translateY(3px); }
    }
  </style>
</head>
<body>

  
  <div class="stage">
    <svg viewBox="0 0 320 140" width="100%" height="100%" style="overflow: visible;">
      
      <line x1="20" y1="128" x2="300" y2="128" stroke="#cbd5e1" stroke-width="3" stroke-linecap="round" />

      
      <path class="stream" d="M 125 45 Q 165 48 185 85" fill="none" />

      
      <g transform="translate(65, 10) rotate(35, 60, 40)">
        
        <path d="M 25 10 L 35 75 Q 35 80 40 80 L 80 80 Q 85 80 85 75 L 95 10 Z" fill="#2563eb" />
        
        <path d="M 27 15 L 35 73 Q 36 77 40 77 L 80 77 Q 84 77 84 73 L 93 15 Z" fill="#38bdf8" opacity="0.9" />
        <ellipse cx="60" cy="15" rx="33" ry="8" fill="#60a5fa" />
        <ellipse cx="60" cy="15" rx="30" ry="6" fill="#0284c7" />
        <text x="60" y="52" text-anchor="middle" class="cup-label" fill="#ffffff" font-size="13">Cup A</text>
      </g>

      
      <g transform="translate(145, 38)">
        
        <rect x="15" y="10" width="60" height="80" rx="6" fill="rgba(241, 245, 249, 0.6)" stroke="#94a3b8" stroke-width="3" />
        
        <ellipse cx="45" cy="10" rx="30" ry="5" fill="#e2e8f0" stroke="#94a3b8" stroke-width="2" />
        
        <rect id="stream-fill" x="18" y="55" width="54" height="32" rx="3" fill="#38bdf8" />
        <ellipse id="stream-surface" cx="45" cy="55" rx="27" ry="4" fill="#60a5fa" />
        <text x="45" y="76" text-anchor="middle" class="cup-label">Jar B</text>
      </g>
    </svg>
  </div>

  
  <div class="results-grid">
    
    <div class="result-card active" id="card-spill" onclick="selectCard(0)">
      <svg class="result-svg" viewBox="0 0 100 100">
        
        <rect x="25" y="28" width="50" height="62" rx="5" fill="#f8fafc" stroke="#94a3b8" stroke-width="2.5" />
        
        <rect x="27" y="28" width="46" height="60" rx="3" fill="#38bdf8" />
        
        <path d="M 20 28 Q 50 20 80 28 Q 85 45 82 50 Q 80 34 75 30 L 25 30 Q 20 34 18 50 Q 15 45 20 28 Z" fill="#0284c7" />
        
        <g class="splash" fill="#0284c7">
          <circle cx="14" cy="56" r="3" />
          <circle cx="86" cy="56" r="3" />
          <circle cx="18" cy="20" r="2.5" />
          <circle cx="82" cy="20" r="2.5" />
        </g>
        <ellipse cx="50" cy="28" rx="25" ry="4" fill="#60a5fa" />
      </svg>
      <div class="card-title">Spills Over!</div>
      <div class="card-sub">Holds Less</div>
    </div>

    
    <div class="result-card" id="card-room" onclick="selectCard(1)">
      <svg class="result-svg" viewBox="0 0 100 100">
        
        <rect x="25" y="22" width="50" height="68" rx="5" fill="#f8fafc" stroke="#94a3b8" stroke-width="2.5" />
        
        <rect x="27" y="58" width="46" height="30" rx="3" fill="#38bdf8" />
        <ellipse cx="50" cy="58" rx="23" ry="3.5" fill="#60a5fa" />
        
        <g class="gap-arrow" stroke="#f59e0b" stroke-width="2" fill="none">
          <line x1="50" y1="28" x2="50" y2="48" stroke-dasharray="2 2" />
          <polyline points="46,44 50,49 54,44" stroke-linecap="round" stroke-linejoin="round" />
        </g>
        <ellipse cx="50" cy="22" rx="25" ry="4" fill="none" stroke="#94a3b8" stroke-width="2" />
      </svg>
      <div class="card-title">Room Left!</div>
      <div class="card-sub">Holds More</div>
    </div>

    
    <div class="result-card" id="card-equal" onclick="selectCard(2)">
      <svg class="result-svg" viewBox="0 0 100 100">
        
        <rect x="25" y="25" width="50" height="65" rx="5" fill="#f8fafc" stroke="#94a3b8" stroke-width="2.5" />
        
        <rect x="27" y="26" width="46" height="62" rx="3" fill="#38bdf8" />
        <ellipse cx="50" cy="26" rx="23" ry="4" fill="#22c55e" opacity="0.3" />
        <ellipse cx="50" cy="26" rx="23" ry="4" fill="none" stroke="#22c55e" stroke-width="2.5" />
        
        <circle cx="50" cy="56" r="11" fill="#22c55e" />
        <polyline points="45,56 48,60 56,52" fill="none" stroke="#ffffff" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round" />
      </svg>
      <div class="card-title">Just Right!</div>
      <div class="card-sub">Holds Same</div>
    </div>
  </div>

  <script>
    const cards = [
      document.getElementById('card-spill'),
      document.getElementById('card-room'),
      document.getElementById('card-equal')
    ];

    const streamFill = document.getElementById('stream-fill');
    const streamSurface = document.getElementById('stream-surface');

    // Jar fill visual configurations corresponding to 3 results
    const fillConfigs = [
      { y: 38, height: 49, topY: 38 }, // Spill (full)
      { y: 62, height: 25, topY: 62 }, // Room left (half)
      { y: 44, height: 43, topY: 44 }  // Just right (exact)
    ];

    let currentIndex = 0;

    function selectCard(index) {
      currentIndex = index;
      cards.forEach((c, i) => {
        if (i === index) {
          c.classList.add('active');
        } else {
          c.classList.remove('active');
        }
      });

      // Update the main pouring jar water level
      const cfg = fillConfigs[index];
      streamFill.setAttribute('y', cfg.y);
      streamFill.setAttribute('height', cfg.height);
      streamSurface.setAttribute('cy', cfg.topY);
    }

    // Auto-cycle through states slowly for Grade 2 observation
    setInterval(() => {
      currentIndex = (currentIndex + 1) % 3;
      selectCard(currentIndex);
    }, 3500);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Size vs. Weight Comparison</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: #ffffff;
      padding: 16px 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
    }

    .container {
      width: 100%;
      max-width: 460px;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }

    /* Header */
    .header-text {
      text-align: center;
    }
    .header-title {
      font-size: 16px;
      font-weight: 800;
      color: #1e2945;
    }
    .header-subtitle {
      font-size: 12px;
      color: #64748b;
      margin-top: 2px;
    }

    /* Toggle bar */
    .controls {
      display: flex;
      justify-content: center;
      gap: 8px;
    }
    .btn {
      padding: 8px 16px;
      border-radius: 20px;
      border: 1.5px solid #cbd5e1;
      background: #f8fafc;
      color: #1e2945;
      font-size: 13px;
      font-weight: 700;
      cursor: pointer;
      transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
    }
    /* Contrast ratio > 4.5:1 with white text on #0369a1 */
    .btn.active {
      background: #0369a1;
      color: #ffffff;
      border-color: #0369a1;
      box-shadow: 0 2px 6px rgba(3, 105, 161, 0.3);
    }

    /* Comparison Stage */
    .stage {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      position: relative;
    }

    .side-card {
      background: #ffffff;
      border: 1.5px solid #e2e8f0;
      border-radius: 14px;
      padding: 14px 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
      height: 255px;
      overflow: hidden;
    }

    /* Labels */
    .size-tag {
      font-size: 11px;
      font-weight: 700;
      color: #64748b;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }
    .weight-tag {
      font-size: 14px;
      font-weight: 800;
      margin-top: 2px;
    }
    .lighter { color: #0284c7; }
    .heavier { color: #ea580c; }

    /* Arm & Object Assembly */
    .heft-assembly {
      position: absolute;
      bottom: 24px;
      width: 100%;
      display: flex;
      flex-direction: column;
      align-items: center;
      transition: transform 0.5s cubic-bezier(0.34, 1.4, 0.64, 1);
    }

    /* Left: Balloon */
    .balloon-wrapper {
      position: relative;
      display: flex;
      flex-direction: column;
      align-items: center;
      animation: floatSlow 3s ease-in-out infinite alternate;
    }
    @keyframes floatSlow {
      0% { transform: translateY(0px); }
      100% { transform: translateY(-4px); }
    }
    .balloon {
      width: 66px;
      height: 76px;
      background: radial-gradient(circle at 30% 30%, #ff85a2, #f43f5e);
      border-radius: 50% 50% 50% 50% / 45% 45% 55% 55%;
      box-shadow: inset -4px -4px 8px rgba(0,0,0,0.15), 0 4px 10px rgba(244,63,94,0.2);
      position: relative;
    }
    .balloon-shine {
      position: absolute;
      top: 14px;
      left: 14px;
      width: 12px;
      height: 20px;
      border-radius: 50%;
      background: rgba(255, 255, 255, 0.65);
      transform: rotate(-25deg);
    }
    .balloon-knot {
      width: 8px;
      height: 6px;
      background: #e11d48;
      clip-path: polygon(0 100%, 50% 0, 100% 100%);
      margin-top: -2px;
    }
    .balloon-string {
      width: 1.5px;
      height: 16px;
      background: #94a3b8;
    }

    /* Right: Heavy Stone */
    .stone-wrapper {
      position: relative;
      display: flex;
      flex-direction: column;
      align-items: center;
      height: 94px;
      justify-content: flex-end;
    }
    .stone {
      width: 28px;
      height: 24px;
      background: radial-gradient(circle at 35% 30%, #64748b, #334155);
      border-radius: 8px 12px 10px 14px;
      box-shadow: 0 3px 6px rgba(0,0,0,0.3);
      margin-bottom: 4px;
    }

    /* Hands */
    .hand {
      font-size: 30px;
      line-height: 1;
      filter: drop-shadow(0 2px 4px rgba(0,0,0,0.15));
      user-select: none;
      height: 30px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    /* Arrow cue */
    .weight-arrow {
      position: absolute;
      right: 12px;
      bottom: 64px;
      display: flex;
      flex-direction: column;
      align-items: center;
      opacity: 0;
      transform: translateY(-8px);
      transition: opacity 0.4s ease, transform 0.4s ease;
      pointer-events: none;
    }
    .weight-arrow svg {
      width: 18px;
      height: 30px;
      fill: #ea580c;
      filter: drop-shadow(0 2px 4px rgba(234, 88, 12, 0.25));
    }

    /* Height reference baseline */
    .reference-line {
      position: absolute;
      left: 6%;
      right: 6%;
      bottom: 40px;
      border-top: 1.5px dashed #94a3b8;
      z-index: 1;
      pointer-events: none;
    }
    .reference-label {
      position: absolute;
      right: 8px;
      top: -14px;
      font-size: 9px;
      font-weight: 700;
      color: #94a3b8;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    /* Hefting Active State */
    .is-hefting .left-assembly {
      transform: translateY(-12px);
    }
    .is-hefting .right-assembly {
      transform: translateY(20px);
    }
    .is-hefting .weight-arrow {
      opacity: 1;
      transform: translateY(0);
    }

    /* Educational Takeaway Box */
    .insight-card {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 12px;
      font-size: 12px;
      line-height: 1.4;
      color: #334155;
      text-align: center;
    }
    .insight-card strong {
      color: #0369a1;
    }
  </style>
</head>
<body>

<div class="container">
  <div class="header-text">
    <div class="header-title">Size Does Not Always Equal Weight</div>
    <div class="header-subtitle">Compare how an object feels when you hold it</div>
  </div>

  
  <div class="controls">
    <button id="btnLook" class="btn" onclick="setState(false)">1. Look (Size)</button>
    <button id="btnHeft" class="btn active" onclick="setState(true)">2. Heft (Weight)</button>
  </div>

  
  <div id="stageArea" class="stage is-hefting">
    <div class="reference-line">
      <span class="reference-label">Level</span>
    </div>

    
    <div class="side-card">
      <div class="size-tag">BIG size</div>
      <div class="weight-tag lighter">LIGHTER</div>

      <div class="heft-assembly left-assembly">
        <div class="balloon-wrapper">
          <div class="balloon"><div class="balloon-shine"></div></div>
          <div class="balloon-knot"></div>
          <div class="balloon-string"></div>
        </div>
        <div class="hand">🫲</div>
      </div>
    </div>

    
    <div class="side-card">
      <div class="size-tag">SMALL size</div>
      <div class="weight-tag heavier">HEAVIER</div>

      <div class="weight-arrow">
        <svg viewBox="0 0 24 36">
          <path d="M10 0 H14 V22 H20 L12 34 L4 22 H10 Z"/>
        </svg>
      </div>

      <div class="heft-assembly right-assembly">
        <div class="stone-wrapper">
          <div class="stone"></div>
        </div>
        <div class="hand">🫱</div>
      </div>
    </div>
  </div>

  
  <div class="insight-card" id="insightText">
    <strong>Hefting:</strong> Gravity pulls harder on the dense stone, pulling the hand down, while the light balloon stays high.
  </div>
</div>

<script>
  function setState(hefting) {
    const stage = document.getElementById('stageArea');
    const btnLook = document.getElementById('btnLook');
    const btnHeft = document.getElementById('btnHeft');
    const insightText = document.getElementById('insightText');

    if (hefting) {
      stage.classList.add('is-hefting');
      btnHeft.classList.add('active');
      btnLook.classList.remove('active');
      insightText.innerHTML = '<strong>Hefting:</strong> Gravity pulls harder on the dense stone, pulling the hand down, while the light balloon stays high.';
    } else {
      stage.classList.remove('is-hefting');
      btnLook.classList.add('active');
      btnHeft.classList.remove('active');
      insightText.innerHTML = '<strong>Looking:</strong> The balloon looks much bigger, but size alone cannot tell you how heavy an object is.';
    }
  }
</script>

</body>
</html>

Comparing Heaviness Directly by Hefting

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

    body {
      width: 100%;
      background-color: #f8f9fa;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      padding: 12px 8px;
      overflow-x: hidden;
    }

    .comparison-grid {
      display: flex;
      flex-direction: row;
      justify-content: center;
      align-items: flex-start;
      gap: 12px;
      width: 100%;
      max-width: 500px;
    }

    .hand-column {
      flex: 1;
      min-width: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
    }

    .badge {
      font-size: 12px;
      font-weight: 600;
      line-height: 1.3;
      text-align: center;
      padding: 6px 8px;
      border-radius: 10px;
      margin-bottom: 8px;
      width: 100%;
      max-width: 180px;
      box-shadow: 0 1px 4px rgba(0,0,0,0.05);
    }

    .badge-heavy {
      background-color: #dcfce7;
      border: 2px solid #16a34a;
      color: #14532d;
    }

    .badge-heavy strong {
      display: block;
      font-size: 15px;
      font-weight: 800;
      color: #14532d;
      letter-spacing: 0.5px;
    }

    .badge-light {
      background-color: #e0f2fe;
      border: 2px solid #0284c7;
      color: #0c4a6e;
    }

    .badge-light strong {
      display: block;
      font-size: 15px;
      font-weight: 800;
      color: #0369a1;
      letter-spacing: 0.5px;
    }

    .visual-stage {
      width: 100%;
      max-width: 180px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      position: relative;
    }

    .svg-scene {
      width: 100%;
      height: auto;
      display: block;
      overflow: visible;
    }

    .baseline-guide {
      stroke: #94a3b8;
      stroke-dasharray: 4 4;
      stroke-width: 1.5;
    }

    @media (min-width: 480px) {
      body {
        padding: 16px;
      }
      .comparison-grid {
        gap: 20px;
      }
      .badge {
        font-size: 13px;
        padding: 8px 12px;
      }
      .badge-heavy strong,
      .badge-light strong {
        font-size: 16px;
      }
    }
  </style>
</head>
<body>

  <div class="comparison-grid">
    
    <div class="hand-column">
      <div class="badge badge-heavy">
        Pushes down more<br>
        <strong>HEAVIER</strong>
      </div>
      
      <div class="visual-stage">
        <svg class="svg-scene" viewBox="0 0 160 170" aria-label="Heavy apple pushing hand downwards">
          
          <line x1="5" y1="75" x2="155" y2="75" class="baseline-guide" />

          
          <g transform="translate(80, 38)">
            <line x1="0" y1="0" x2="0" y2="30" stroke="#15803d" stroke-width="4.5" stroke-linecap="round" />
            <polygon points="-6,27 6,27 0,38" fill="#15803d" />
          </g>

          
          <g transform="translate(25, 78)">
            
            <path d="M 0,78 Q 20,68 50,54 L 55,74 Q 25,86 0,92 Z" fill="#fed7aa" stroke="#ea580c" stroke-width="2" />
            
            
            <g transform="translate(72, 2)">
              
              <ellipse cx="-10" cy="18" rx="19" ry="21" fill="#ef4444" />
              <ellipse cx="10" cy="18" rx="19" ry="21" fill="#dc2626" />
              <ellipse cx="0" cy="22" rx="17" ry="17" fill="#ef4444" />
              
              <ellipse cx="-12" cy="12" rx="5" ry="8" fill="#fca5a5" transform="rotate(-20 -12 12)" />
              
              <path d="M 0,0 Q 5,-11 13,-13 Q 10,-9 3,-2 Z" fill="#78350f" />
              
              <path d="M 2,-5 Q 15,-15 21,-7 Q 13,-1 2,-5 Z" fill="#16a34a" />
            </g>

            
            <ellipse cx="65" cy="42" rx="27" ry="13" fill="#fed7aa" stroke="#ea580c" stroke-width="2" transform="rotate(-8 65 42)" />
            
            <rect x="48" y="30" width="10" height="17" rx="5" fill="#fcd34d" stroke="#ea580c" stroke-width="1.5" />
            <rect x="58" y="28" width="10" height="19" rx="5" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
            <rect x="68" y="29" width="10" height="18" rx="5" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
            <rect x="78" y="32" width="9" height="15" rx="4.5" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
            
            <path d="M 38,34 Q 44,20 54,26 Q 48,38 40,40 Z" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
          </g>
        </svg>
      </div>
    </div>

    
    <div class="hand-column">
      <div class="badge badge-light">
        Pushes down less<br>
        <strong>LIGHTER</strong>
      </div>
      
      <div class="visual-stage">
        <svg class="svg-scene" viewBox="0 0 160 170" aria-label="Light feather with hand held up high">
          
          <line x1="5" y1="75" x2="155" y2="75" class="baseline-guide" />

          
          <g transform="translate(80, 22)">
            <line x1="0" y1="0" x2="0" y2="15" stroke="#0284c7" stroke-width="2.5" stroke-dasharray="3 2" stroke-linecap="round" />
            <polygon points="-4,13 4,13 0,20" fill="#0284c7" />
          </g>

          
          <g transform="translate(25, 42)">
            
            <path d="M 0,55 Q 25,50 50,45 L 52,65 Q 25,70 0,75 Z" fill="#fed7aa" stroke="#ea580c" stroke-width="2" />

            
            <g transform="translate(70, -2) rotate(-22)">
              
              <path d="M 0,35 C -16,20 -16,-5 0,-25 C 16,-5 16,20 0,35 Z" fill="#fef08a" stroke="#facc15" stroke-width="1.5" />
              
              <path d="M 0,-28 Q -1,5 0,42" stroke="#ca8a04" stroke-width="2" fill="none" stroke-linecap="round" />
              
              <line x1="0" y1="-10" x2="-8" y2="-16" stroke="#eab308" stroke-width="1.2" />
              <line x1="0" y1="0" x2="-10" y2="-5" stroke="#eab308" stroke-width="1.2" />
              <line x1="0" y1="10" x2="-8" y2="5" stroke="#eab308" stroke-width="1.2" />
              <line x1="0" y1="-10" x2="8" y2="-16" stroke="#eab308" stroke-width="1.2" />
              <line x1="0" y1="0" x2="10" y2="-5" stroke="#eab308" stroke-width="1.2" />
              <line x1="0" y1="10" x2="8" y2="5" stroke="#eab308" stroke-width="1.2" />
            </g>

            
            <ellipse cx="65" cy="45" rx="26" ry="12" fill="#fed7aa" stroke="#ea580c" stroke-width="2" transform="rotate(2 65 45)" />
            
            <rect x="50" y="35" width="9" height="18" rx="4.5" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
            <rect x="60" y="32" width="9" height="21" rx="4.5" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
            <rect x="70" y="34" width="9" height="19" rx="4.5" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
            <rect x="80" y="38" width="8" height="15" rx="4.5" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
            
            <path d="M 40,38 Q 44,25 54,30 Q 49,42 42,43 Z" fill="#fed7aa" stroke="#ea580c" stroke-width="1.5" />
          </g>
        </svg>
      </div>
    </div>
  </div>

</body>
</html>

OGM.2.MD.3

Aligned learning resources

Related diagrams