<!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>Comparing Lengths by Aligning Ends</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      width: 100%;
      background: #ffffff;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 12px;
      user-select: none;
    }

    .diagram-area {
      width: 100%;
      max-width: 350px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
    }

    /* Badge */
    .badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #f0fdf4;
      border: 1.5px solid #86efac;
      color: #166534;
      font-size: 14px;
      font-weight: 700;
      padding: 6px 14px;
      border-radius: 999px;
      box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    }

    /* SVG Canvas */
    .svg-container {
      width: 100%;
      aspect-ratio: 1 / 0.85;
      position: relative;
    }

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

    /* Interactive controls */
    .btn-toggle {
      margin-top: 4px;
      background: #f8fafc;
      border: 1.5px solid #cbd5e1;
      color: #1e2945;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 16px;
      border-radius: 20px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background-color 0.2s, border-color 0.2s;
    }

    .btn-toggle:active {
      background: #e2e8f0;
    }

    .guide-line {
      stroke-dasharray: 6, 4;
      transition: opacity 0.3s ease;
    }

    .callout-tag {
      font-size: 12px;
      font-weight: 700;
      transition: opacity 0.3s ease;
    }
  </style>
</head>
<body>

  <div class="diagram-area">
    
    <div class="badge" id="mainBadge">
      <span>⭐</span> Equal Length (The Same!)
    </div>

    
    <div class="svg-container">
      <svg viewBox="0 0 320 250">
        <defs>
          
          <linearGradient id="stickGrad1" x1="0" y1="0" x2="1" y2="0">
            <stop offset="0%" stop-color="#b45309" />
            <stop offset="40%" stop-color="#d97706" />
            <stop offset="100%" stop-color="#92400e" />
          </linearGradient>
          
          <linearGradient id="stickGrad2" x1="0" y1="0" x2="1" y2="0">
            <stop offset="0%" stop-color="#a16207" />
            <stop offset="40%" stop-color="#ca8a04" />
            <stop offset="100%" stop-color="#854d0e" />
          </linearGradient>
          
          <linearGradient id="groundGrad" x1="0" y1="0" x2="0" y2="1">
            <stop offset="0%" stop-color="#4ade80" />
            <stop offset="100%" stop-color="#22c55e" />
          </linearGradient>
        </defs>

        
        <g id="topGuideGroup">
          <line x1="45" y1="48" x2="275" y2="48" class="guide-line" stroke="#2563eb" stroke-width="2" />
          
          <rect x="100" y="32" width="120" height="24" rx="12" fill="#eff6ff" stroke="#3b82f6" stroke-width="1.5" />
          <text x="160" y="48" text-anchor="middle" dominant-baseline="central" class="callout-tag" fill="#1d4ed8">Top ends match! ✓</text>
        </g>

        
        <g transform="translate(100, 48)">
          
          <rect x="-9" y="0" width="18" height="152" rx="9" fill="url(#stickGrad1)" stroke="#78350f" stroke-width="1.5" />
          
          <path d="M 9 50 Q 20 44 22 36 Q 14 42 9 46" fill="#16a34a" stroke="#15803d" stroke-width="0.8" />
          <line x1="-3" y1="30" x2="3" y2="30" stroke="#78350f" stroke-width="1.5" stroke-linecap="round" />
          <line x1="-4" y1="95" x2="2" y2="95" stroke="#78350f" stroke-width="1.5" stroke-linecap="round" />
        </g>

        
        <g transform="translate(220, 48)">
          
          <rect x="-9" y="0" width="18" height="152" rx="9" fill="url(#stickGrad2)" stroke="#713f12" stroke-width="1.5" />
          
          <path d="M -9 80 Q -20 74 -22 66 Q -14 72 -9 76" fill="#16a34a" stroke="#15803d" stroke-width="0.8" />
          <line x1="-2" y1="55" x2="4" y2="55" stroke="#713f12" stroke-width="1.5" stroke-linecap="round" />
          <line x1="-3" y1="120" x2="3" y2="120" stroke="#713f12" stroke-width="1.5" stroke-linecap="round" />
        </g>

        
        <rect x="20" y="200" width="280" height="14" rx="7" fill="url(#groundGrad)" stroke="#16a34a" stroke-width="1.5" />

        
        <g id="bottomGuideGroup">
          <rect x="90" y="218" width="140" height="22" rx="6" fill="#f0fdf4" stroke="#86efac" stroke-width="1" />
          <text x="160" y="229" text-anchor="middle" dominant-baseline="central" class="callout-tag" fill="#15803d">Bottom ends aligned ✓</text>
        </g>
      </svg>
    </div>

    
    <button class="btn-toggle" id="toggleBtn" onclick="toggleGuides()">
      <span id="btnIcon">👁️</span> <span id="btnText">Toggle Alignment Lines</span>
    </button>
  </div>

  <script>
    let guidesVisible = true;

    function toggleGuides() {
      guidesVisible = !guidesVisible;
      const topGroup = document.getElementById('topGuideGroup');
      const bottomGroup = document.getElementById('bottomGuideGroup');
      const btnIcon = document.getElementById('btnIcon');
      const btnText = document.getElementById('btnText');

      if (guidesVisible) {
        topGroup.style.opacity = '1';
        bottomGroup.style.opacity = '1';
        btnIcon.textContent = '👁️';
        btnText.textContent = 'Hide Alignment Lines';
      } else {
        topGroup.style.opacity = '0';
        bottomGroup.style.opacity = '0';
        btnIcon.textContent = '✨';
        btnText.textContent = 'Show Alignment Lines';
      }
    }
  </script>
</body>
</html>

Comparing Lengths Directly by Aligning Ends

<!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>Comparing Lengths by Aligning Ends</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      background: transparent;
      color: #1e2945;
      display: flex;
      justify-content: center;
      align-items: center;
      padding: 10px;
      min-height: 100%;
    }
    .wrapper {
      width: 100%;
      max-width: 350px;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
    }
    .panel {
      background: #f8fafc;
      border-radius: 14px;
      padding: 10px 8px 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
    }
    .panel.wrong {
      border: 2px solid #fecaca;
      background: #fffafa;
    }
    .panel.correct {
      border: 2px solid #bbf7d0;
      background: #f0fdf4;
    }
    .header {
      font-size: 14px;
      font-weight: 700;
      text-align: center;
      margin-bottom: 8px;
    }
    .wrong .header {
      color: #dc2626;
    }
    .correct .header {
      color: #16a34a;
    }
    .stage {
      position: relative;
      width: 100%;
      height: 180px;
      background: #ffffff;
      border-radius: 10px;
      border: 1px solid #e2e8f0;
      overflow: hidden;
    }
    .stick {
      position: absolute;
      width: 22px;
      border-radius: 11px;
      box-shadow: 0 2px 4px rgba(0,0,0,0.08);
      transition: all 0.4s ease;
    }
    .stick-orange {
      background: linear-gradient(180deg, #fb923c, #ea580c);
      border: 2px solid #c2410c;
    }
    .stick-blue {
      background: linear-gradient(180deg, #38bdf8, #0284c7);
      border: 2px solid #0369a1;
    }
    
    /* Left Panel Sticks */
    .stick-left-orange {
      left: 20%;
      bottom: 22px;
      height: 120px;
    }
    .stick-left-blue {
      right: 20%;
      bottom: 80px;
      height: 72px;
    }

    /* Right Panel Sticks */
    .stick-right-orange {
      left: 20%;
      bottom: 22px;
      height: 120px;
    }
    .stick-right-blue {
      right: 20%;
      bottom: 22px;
      height: 72px;
    }

    /* Baselines */
    .baseline-green {
      position: absolute;
      bottom: 22px;
      left: 8px;
      right: 8px;
      height: 0;
      border-bottom: 2.5px dashed #16a34a;
      z-index: 5;
    }
    .mismatch-line-1 {
      position: absolute;
      bottom: 22px;
      left: 14%;
      width: 35%;
      border-bottom: 2px dashed #dc2626;
    }
    .mismatch-line-2 {
      position: absolute;
      bottom: 80px;
      right: 14%;
      width: 35%;
      border-bottom: 2px dashed #dc2626;
    }

    .footer-label {
      margin-top: 8px;
      font-size: 12px;
      font-weight: 600;
      text-align: center;
      line-height: 1.2;
    }
    .wrong .footer-label {
      color: #991b1b;
    }
    .correct .footer-label {
      color: #166534;
    }
    .indicator-badge {
      position: absolute;
      top: 6px;
      right: 6px;
      font-size: 14px;
      line-height: 1;
    }
  </style>
</head>
<body>

<div class="wrapper">
  
  <div class="panel wrong">
    <div class="header">❌ Not Fair!</div>
    <div class="stage">
      <div class="mismatch-line-1"></div>
      <div class="mismatch-line-2"></div>
      <div class="stick stick-orange stick-left-orange"></div>
      <div class="stick stick-blue stick-left-blue"></div>
    </div>
    <div class="footer-label">Ends do not<br>match!</div>
  </div>

  
  <div class="panel correct">
    <div class="header">✅ Fair Start!</div>
    <div class="stage">
      <div class="baseline-green"></div>
      <div class="stick stick-orange stick-right-orange"></div>
      <div class="stick stick-blue stick-right-blue"></div>
    </div>
    <div class="footer-label">Bottom ends<br>aligned!</div>
  </div>
</div>

</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">
  <title>Comparing Lengths</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      user-select: none;
      -webkit-user-select: none;
    }

    body {
      width: 100%;
      height: 100%;
      min-height: 340px;
      font-family: system-ui, -apple-system, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-end;
      position: relative;
      overflow: hidden;
      padding: 16px 12px 10px;
    }

    /* Comparison Stage Area */
    .stage {
      position: relative;
      width: 100%;
      max-width: 320px;
      height: 250px;
      display: flex;
      justify-content: space-around;
      align-items: flex-end;
      padding: 0 10px;
    }

    /* Column for each stick + badge */
    .stick-col {
      position: relative;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-end;
      width: 120px;
      height: 100%;
      cursor: pointer;
    }

    /* Kid-friendly Badges */
    .badge {
      font-size: 15px;
      font-weight: 800;
      padding: 6px 12px;
      border-radius: 20px;
      margin-bottom: 12px;
      box-shadow: 0 3px 8px rgba(0, 0, 0, 0.08);
      display: flex;
      align-items: center;
      gap: 4px;
      transition: transform 0.2s ease, box-shadow 0.2s ease;
      white-space: nowrap;
    }

    .badge-longer {
      background: #fef08a;
      color: #854d0e;
      border: 2px solid #facc15;
    }

    .badge-shorter {
      background: #dcfce7;
      color: #166534;
      border: 2px solid #86efac;
    }

    .stick-col:active .badge {
      transform: scale(0.96);
    }

    /* Stick A - Tall */
    .stick-a {
      position: relative;
      width: 24px;
      height: 180px;
      background: linear-gradient(90deg, #6d4019 0%, #8b5528 50%, #563011 100%);
      border-radius: 12px 12px 4px 4px;
      box-shadow: 2px 2px 6px rgba(0,0,0,0.15);
    }

    /* Stick B - Short */
    .stick-b {
      position: relative;
      width: 18px;
      height: 110px;
      background: linear-gradient(90deg, #af8558 0%, #caa479 50%, #8e6841 100%);
      border-radius: 10px 10px 4px 4px;
      box-shadow: 2px 2px 5px rgba(0,0,0,0.12);
    }

    /* Cute details on sticks */
    .leaf {
      position: absolute;
      top: 24px;
      right: -14px;
      font-size: 20px;
      transform: rotate(25deg);
      pointer-events: none;
    }

    .twig-branch {
      position: absolute;
      top: 30px;
      left: -8px;
      width: 10px;
      height: 6px;
      border-top: 4px solid #8e6841;
      border-radius: 4px 0 0 0;
      transform: rotate(-25deg);
    }

    /* Sparkling effect for longer stick */
    .sparkle-container {
      position: absolute;
      top: -24px;
      display: flex;
      align-items: center;
      justify-content: center;
      pointer-events: none;
    }

    .sparkle-icon {
      font-size: 22px;
      animation: floatSparkle 2.2s infinite ease-in-out;
    }

    @keyframes floatSparkle {
      0%, 100% {
        transform: translateY(0) scale(1);
        opacity: 0.9;
      }
      50% {
        transform: translateY(-5px) scale(1.18);
        opacity: 1;
      }
    }

    /* Dashed alignment height comparison line */
    .diff-line {
      position: absolute;
      bottom: 110px;
      left: 15%;
      width: 70%;
      border-top: 2px dashed #94a3b8;
      pointer-events: none;
      opacity: 0.6;
    }

    /* Start Line Ground */
    .ground-container {
      width: 100%;
      max-width: 320px;
      display: flex;
      flex-direction: column;
      align-items: center;
      z-index: 2;
    }

    .start-line {
      width: 100%;
      height: 12px;
      background: #22c55e;
      border-radius: 6px;
      box-shadow: 0 2px 4px rgba(34, 197, 94, 0.3);
    }

    .ground-label {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      margin-top: 8px;
      padding: 5px 12px;
      background: #f0fdf4;
      border: 1.5px solid #86efac;
      border-radius: 12px;
      font-size: 13px;
      font-weight: 700;
      color: #15803d;
    }
  </style>
</head>
<body>

  
  <div class="stage">
    <div class="diff-line"></div>

    
    <div class="stick-col" id="stickA" onclick="tapStick('high')">
      <div class="sparkle-container">
        <span class="sparkle-icon">✨</span>
      </div>
      <div class="badge badge-longer">Longer 🌟</div>
      <div class="stick-a">
        <span class="leaf">🍃</span>
      </div>
    </div>

    
    <div class="stick-col" id="stickB" onclick="tapStick('low')">
      <div class="badge badge-shorter">Shorter 🌿</div>
      <div class="stick-b">
        <div class="twig-branch"></div>
      </div>
    </div>
  </div>

  
  <div class="ground-container">
    <div class="start-line"></div>
    <div class="ground-label">
      <span>Both ends touch here!</span>
      <span>⬇️</span>
    </div>
  </div>

  <script>
    function tapStick(pitch) {
      try {
        const ctx = new (window.AudioContext || window.webkitAudioContext)();
        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'triangle';
        osc.frequency.setValueAtTime(pitch === 'high' ? 587.33 : 392.00, ctx.currentTime); // D5 or G4
        gain.gain.setValueAtTime(0.2, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 0.35);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + 0.35);
      } catch (e) {}
    }
  </script>
</body>
</html>

<!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;
      user-select: none;
      -webkit-user-select: none;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 12px 10px;
      gap: 12px;
      overflow-x: hidden;
    }

    /* Main Balance Stage */
    .stage {
      position: relative;
      width: 100%;
      max-width: 440px;
      height: 210px;
      display: flex;
      justify-content: center;
      align-items: center;
    }

    /* Fulcrum Base */
    .base {
      position: absolute;
      bottom: 10px;
      left: 50%;
      transform: translateX(-50%);
      width: 0;
      height: 0;
      border-left: 24px solid transparent;
      border-right: 24px solid transparent;
      border-bottom: 48px solid #94a3b8;
      z-index: 1;
    }
    .base-post {
      position: absolute;
      bottom: 42px;
      left: 50%;
      transform: translateX(-50%);
      width: 12px;
      height: 48px;
      background: #64748b;
      border-radius: 6px;
      z-index: 2;
    }

    /* Seesaw Beam - tilts left (Hand 1) DOWN, right (Hand 2) UP */
    .beam-container {
      position: absolute;
      top: 126px;
      left: 50%;
      width: 82%;
      max-width: 350px;
      height: 10px;
      transform: translate(-50%, -50%) rotate(-9deg);
      transform-origin: center center;
      transition: transform 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
      z-index: 3;
    }
    .beam-bar {
      width: 100%;
      height: 10px;
      background: #334155;
      border-radius: 5px;
      box-shadow: 0 3px 6px rgba(0,0,0,0.12);
    }
    .pivot-dot {
      position: absolute;
      top: 50%;
      left: 50%;
      width: 20px;
      height: 20px;
      background: #0ea5e9;
      border: 3px solid #ffffff;
      border-radius: 50%;
      transform: translate(-50%, -50%);
      box-shadow: 0 2px 4px rgba(0,0,0,0.15);
      z-index: 4;
    }

    /* Hand / Plate Units */
    .side {
      position: absolute;
      top: 5px;
      display: flex;
      flex-direction: column;
      align-items: center;
      cursor: pointer;
      -webkit-tap-highlight-color: transparent;
    }
    .side-left {
      left: 0;
      transform: translate(-50%, -88%);
    }
    .side-right {
      right: 0;
      transform: translate(50%, -88%);
    }

    .hand-card {
      background: #ffffff;
      border: 2px solid #e2e8f0;
      border-radius: 14px;
      padding: 6px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      box-shadow: 0 3px 10px rgba(0,0,0,0.06);
      transition: box-shadow 0.2s ease;
    }
    .side:active .hand-card {
      background: #f1f5f9;
    }

    .hand-label {
      font-size: 12px;
      font-weight: 700;
      color: #64748b;
      letter-spacing: 0.4px;
      margin-bottom: 2px;
    }

    .item-emoji {
      font-size: 38px;
      line-height: 1;
      filter: drop-shadow(0 2px 3px rgba(0,0,0,0.1));
    }

    .hand-emoji {
      font-size: 24px;
      margin-top: -2px;
      line-height: 1;
    }

    .motion-indicator {
      font-size: 16px;
      font-weight: 800;
      margin-top: 2px;
      line-height: 1;
    }
    .side-left .motion-indicator {
      color: #dc2626;
    }
    .side-right .motion-indicator {
      color: #16a34a;
    }

    /* Badges */
    .badges-row {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 10px;
      width: 100%;
      max-width: 440px;
    }
    .badge {
      flex: 1 1 150px;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      padding: 10px 12px;
      border-radius: 12px;
      font-size: 15px;
      font-weight: 700;
      text-align: center;
      box-shadow: 0 2px 4px rgba(0,0,0,0.04);
    }
    .badge-heavy {
      background: #fee2e2;
      color: #991b1b;
      border: 2px solid #fecaca;
    }
    .badge-light {
      background: #dcfce7;
      color: #166534;
      border: 2px solid #bbf7d0;
    }

    /* Tap Control Button */
    .tap-btn {
      background: #0ea5e9;
      color: #ffffff;
      border: none;
      border-radius: 12px;
      padding: 10px 22px;
      font-size: 15px;
      font-weight: 700;
      cursor: pointer;
      box-shadow: 0 3px 8px rgba(14, 165, 233, 0.3);
      display: flex;
      align-items: center;
      gap: 8px;
      transition: background-color 0.2s;
      -webkit-tap-highlight-color: transparent;
    }
    .tap-btn:active {
      background: #0284c7;
    }

    /* Wobble animation */
    @keyframes wobbleBeam {
      0% { transform: translate(-50%, -50%) rotate(-9deg); }
      25% { transform: translate(-50%, -50%) rotate(-15deg); }
      50% { transform: translate(-50%, -50%) rotate(-3deg); }
      75% { transform: translate(-50%, -50%) rotate(-12deg); }
      100% { transform: translate(-50%, -50%) rotate(-9deg); }
    }
    .wobbling {
      animation: wobbleBeam 0.85s ease-in-out;
    }

    @media (max-width: 380px) {
      .stage {
        height: 195px;
      }
      .beam-container {
        top: 118px;
        width: 80%;
      }
      .item-emoji {
        font-size: 32px;
      }
      .hand-emoji {
        font-size: 20px;
      }
      .hand-card {
        padding: 5px 8px;
      }
      .badge {
        font-size: 14px;
        padding: 8px 10px;
      }
      .tap-btn {
        padding: 8px 18px;
        font-size: 14px;
      }
    }
  </style>
</head>
<body>

  
  <div class="stage" aria-label="Hands weighing an apple and a leaf">
    <div class="base-post"></div>
    <div class="base"></div>

    <div class="beam-container" id="beam">
      <div class="beam-bar"></div>
      <div class="pivot-dot"></div>

      
      <div class="side side-left" id="hand1" title="Tap Hand 1" role="button" aria-label="Hand 1 with Apple">
        <div class="hand-card">
          <div class="hand-label">Hand 1</div>
          <div class="item-emoji">🍎</div>
          <div class="hand-emoji">🫲</div>
          <div class="motion-indicator">⬇️</div>
        </div>
      </div>

      
      <div class="side side-right" id="hand2" title="Tap Hand 2" role="button" aria-label="Hand 2 with Leaf">
        <div class="hand-card">
          <div class="hand-label">Hand 2</div>
          <div class="item-emoji">🍃</div>
          <div class="hand-emoji">🫱</div>
          <div class="motion-indicator">⬆️</div>
        </div>
      </div>
    </div>
  </div>

  
  <div class="badges-row">
    <div class="badge badge-heavy">
      <span>🍎 Apple = Heavier</span>
    </div>
    <div class="badge badge-light">
      <span>🍃 Leaf = Lighter</span>
    </div>
  </div>

  
  <button class="tap-btn" id="wobbleBtn" type="button">
    <span>🤲 Wobble Hands</span>
  </button>

  <script>
    const beam = document.getElementById('beam');
    const wobbleBtn = document.getElementById('wobbleBtn');
    const hand1 = document.getElementById('hand1');
    const hand2 = document.getElementById('hand2');

    function triggerWobble() {
      beam.classList.remove('wobbling');
      void beam.offsetWidth; // Force reflow to restart animation
      beam.classList.add('wobbling');
    }

    wobbleBtn.addEventListener('click', triggerWobble);
    hand1.addEventListener('click', triggerWobble);
    hand2.addEventListener('click', triggerWobble);
  </script>
</body>
</html>

Feeling Heaviness by Holding Objects in Two Hands

<!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 {
      width: 100%;
      height: 100%;
      background: #ffffff;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 16px 12px;
      user-select: none;
    }

    .diagram-area {
      position: relative;
      width: 100%;
      max-width: 500px;
      height: 280px;
      margin-top: 8px;
    }

    /* Hands & Balance SVG */
    .balance-svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }

    /* Left Side: Sponge (High Up) */
    .side-left {
      position: absolute;
      left: 10%;
      top: 6%;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
      transition: transform 0.4s ease;
    }

    /* Right Side: Metal Car (Weighed Down) */
    .side-right {
      position: absolute;
      right: 10%;
      top: 36%;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
      transition: transform 0.4s ease;
    }

    .item-icon {
      line-height: 1;
      filter: drop-shadow(0 4px 6px rgba(0,0,0,0.1));
    }
    .sponge-icon {
      font-size: 68px;
      animation: floatLight 3s ease-in-out infinite;
    }
    .car-icon {
      font-size: 34px;
      animation: pressHeavy 3s ease-in-out infinite;
    }

    .tag {
      font-weight: 800;
      font-size: 16px;
      padding: 6px 14px;
      border-radius: 999px;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      white-space: nowrap;
    }

    .tag-light {
      background: #eff6ff;
      color: #0284c7;
      border: 2px solid #bae6fd;
    }

    .tag-heavy {
      background: #ecfdf5;
      color: #059669;
      border: 2px solid #a7f3d0;
      box-shadow: 0 4px 12px rgba(16, 185, 129, 0.2);
    }

    .hand-label {
      font-size: 42px;
      line-height: 1;
    }

    .weight-arrow {
      font-size: 20px;
      font-weight: 900;
      color: #059669;
      animation: bounceDown 1.5s infinite;
    }

    .feather-icon {
      font-size: 18px;
    }

    /* Footer Result Pill */
    .result-pill {
      background: #f8fafc;
      border: 2px solid #e2e8f0;
      border-radius: 12px;
      padding: 8px 18px;
      font-size: 16px;
      font-weight: 700;
      color: #1e2945;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    @keyframes bounceDown {
      0%, 100% { transform: translateY(0); }
      50% { transform: translateY(5px); }
    }

    @keyframes floatLight {
      0%, 100% { transform: translateY(0); }
      50% { transform: translateY(-6px); }
    }

    @keyframes pressHeavy {
      0%, 100% { transform: translateY(0); }
      50% { transform: translateY(3px); }
    }
  </style>
</head>
<body>

  
  <div class="diagram-area">
    <svg class="balance-svg" viewBox="0 0 400 240" fill="none" xmlns="http://www.w3.org/2000/svg">
      
      <line x1="85" y1="120" x2="315" y2="180" stroke="#94a3b8" stroke-width="8" stroke-linecap="round"/>
      
      
      <polygon points="200,150 180,210 220,210" fill="#64748b" rx="4"/>
      <circle cx="200" cy="150" r="7" fill="#334155"/>
      <rect x="155" y="210" width="90" height="10" rx="5" fill="#475569"/>

      
      <path d="M 85 140 Q 65 110 85 85" stroke="#38bdf8" stroke-width="3" stroke-dasharray="4 4" stroke-linecap="round" fill="none"/>
      
      
      <path d="M 315 150 L 315 195" stroke="#10b981" stroke-width="4" stroke-linecap="round" fill="none"/>
      <polyline points="307,187 315,197 323,187" stroke="#10b981" stroke-width="4" stroke-linecap="round" stroke-linejoin="round" fill="none"/>
    </svg>

    
    <div class="side-left">
      <div class="tag tag-light">
        <span>Big & Light</span>
        <span class="feather-icon">🪶</span>
      </div>
      <div class="item-icon sponge-icon">🧽</div>
      <div class="hand-label">🫲</div>
    </div>

    
    <div class="side-right">
      <div class="tag tag-heavy">
        <span>Small & Heavy</span>
        <span>✓</span>
      </div>
      <div class="item-icon car-icon">🚗</div>
      <div class="hand-label">🫱</div>
    </div>
  </div>

  
  <div class="result-pill">
    <span>🚗 Metal Car</span>
    <span style="color:#059669; font-weight:800;">is Heavier</span>
    <span>than 🧽 Sponge</span>
  </div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Lighter vs Heavier</title>
  <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: #1e293b;
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 10px 6px;
      user-select: none;
      overflow-x: hidden;
      min-height: 100vh;
    }

    .stage {
      width: 100%;
      max-width: 480px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 10px;
      margin: 0 auto;
    }

    .title-banner {
      text-align: center;
      padding: 4px 12px;
    }

    .instruction {
      font-size: 16px;
      font-weight: 800;
      color: #334155;
      letter-spacing: 0.2px;
    }

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

    .hands-container {
      width: 100%;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
      position: relative;
      padding: 18px 2px;
    }

    /* Subtle level guide line behind the cards (clean, no stray text) */
    .reference-line {
      position: absolute;
      top: 50%;
      left: 10px;
      right: 10px;
      border-top: 2px dashed #cbd5e1;
      opacity: 0.7;
      z-index: 0;
      pointer-events: none;
    }

    .hand-card {
      position: relative;
      z-index: 1;
      display: flex;
      flex-direction: column;
      align-items: center;
      padding: 12px 8px 14px;
      border-radius: 18px;
      background: #ffffff;
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
      cursor: pointer;
      transition: border-color 0.3s ease, box-shadow 0.3s ease;
    }

    /* Left hand: Light, buoyant, elevated */
    .hand-card.light {
      background: linear-gradient(180deg, #f0f9ff 0%, #ffffff 100%);
      border: 2px solid #38bdf8;
      animation: floatSmoothLight 4.5s ease-in-out infinite;
    }

    /* Right hand: Heavy, weighted down, dipped */
    .hand-card.heavy {
      background: linear-gradient(180deg, #f8fafc 0%, #f1f5f9 100%);
      border: 2px solid #94a3b8;
      animation: floatSmoothHeavy 4.5s ease-in-out infinite;
    }

    .hand-card:hover {
      box-shadow: 0 6px 16px rgba(0, 0, 0, 0.1);
    }

    /* Smooth, gentle, non-flickering bounce animations */
    @keyframes floatSmoothLight {
      0%, 100% {
        transform: translateY(-12px);
      }
      50% {
        transform: translateY(-20px);
      }
    }

    @keyframes floatSmoothHeavy {
      0%, 100% {
        transform: translateY(12px);
      }
      50% {
        transform: translateY(18px);
      }
    }

    .badge {
      font-size: 14px;
      font-weight: 800;
      padding: 4px 10px;
      border-radius: 999px;
      margin-bottom: 6px;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      white-space: nowrap;
      box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    }

    .badge-light {
      background: #e0f2fe;
      color: #0369a1;
      border: 1.5px solid #7dd3fc;
    }

    .badge-heavy {
      background: #f1f5f9;
      color: #334155;
      border: 1.5px solid #94a3b8;
    }

    .indicator-box {
      height: 24px;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 2px;
    }

    .breeze-icon {
      animation: gentleBreeze 3.5s ease-in-out infinite;
    }

    .arrow-down-icon {
      animation: gentleDrop 3.5s ease-in-out infinite;
    }

    @keyframes gentleBreeze {
      0%, 100% {
        transform: translateY(0px);
        opacity: 0.85;
      }
      50% {
        transform: translateY(-3px);
        opacity: 1;
      }
    }

    @keyframes gentleDrop {
      0%, 100% {
        transform: translateY(0px);
        opacity: 0.85;
      }
      50% {
        transform: translateY(3px);
        opacity: 1;
      }
    }

    .visual-stack {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      position: relative;
      height: 110px;
      width: 100%;
      margin: 2px 0;
    }

    .item-holder {
      position: absolute;
      top: 6px;
      z-index: 2;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .feather-art {
      width: 48px;
      height: 48px;
      filter: drop-shadow(0 3px 6px rgba(56, 189, 248, 0.25));
      animation: gentleSway 4s ease-in-out infinite;
    }

    .rock-art {
      width: 48px;
      height: 48px;
      filter: drop-shadow(0 4px 6px rgba(0, 0, 0, 0.25));
    }

    @keyframes gentleSway {
      0%, 100% {
        transform: rotate(-3deg) translateY(0);
      }
      50% {
        transform: rotate(4deg) translateY(-2px);
      }
    }

    .hand-svg {
      width: 110px;
      height: 65px;
      position: absolute;
      bottom: 2px;
      z-index: 1;
      filter: drop-shadow(0 2px 4px rgba(0,0,0,0.08));
    }

    .level-note {
      margin-top: 6px;
      font-size: 12px;
      font-weight: 700;
      text-align: center;
      line-height: 1.2;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 3px;
    }

    .light-note {
      color: #0284c7;
    }

    .heavy-note {
      color: #475569;
    }

    .fun-tip {
      font-size: 11.5px;
      font-weight: 600;
      color: #64748b;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      padding: 5px 12px;
      border-radius: 12px;
      text-align: center;
      width: 100%;
    }

    @media (max-width: 360px) {
      .stage {
        gap: 8px;
      }
      .instruction {
        font-size: 14.5px;
      }
      .subtitle {
        font-size: 11px;
      }
      .hands-container {
        gap: 6px;
        padding: 14px 0;
      }
      .hand-card {
        padding: 10px 4px 12px;
        border-radius: 14px;
      }
      .badge {
        font-size: 12px;
        padding: 3px 8px;
      }
      .hand-svg {
        width: 96px;
        height: 58px;
      }
      .feather-art, .rock-art {
        width: 40px;
        height: 40px;
      }
      .level-note {
        font-size: 11px;
      }
      .fun-tip {
        font-size: 10.5px;
        padding: 4px 8px;
      }
    }
  </style>
</head>
<body>
  <div class="stage">
    <div class="title-banner">
      <div class="instruction">Comparing Weights</div>
      <div class="subtitle">Heavy things go down • Light things stay up!</div>
    </div>
    
    <div class="hands-container">
      
      <div class="reference-line"></div>

      
      <div class="hand-card light" id="card-light" onclick="highlightCard('light')">
        <div class="badge badge-light">Lighter 🪶</div>
        
        
        <div class="indicator-box">
          <svg class="breeze-icon" width="40" height="20" viewBox="0 0 40 20" fill="none">
            <path d="M 6 15 L 6 5 M 3 8 L 6 4 L 9 8" stroke="#0284c7" stroke-width="2.2" stroke-linecap="round" stroke-linejoin="round"/>
            <path d="M 14 11 C 18 11 20 6 25 6 C 28 6 30 7.5 30 9 C 30 10.5 28.5 11.5 27 11.5 C 25.5 11.5 25 10.5 25 9.5" stroke="#0284c7" stroke-width="2" stroke-linecap="round"/>
            <path d="M 16 15 C 21 15 24 12 29 12 C 33 12 36 14 36 15.5" stroke="#38bdf8" stroke-width="1.8" stroke-linecap="round"/>
          </svg>
        </div>

        <div class="visual-stack">
          
          <div class="item-holder">
            <svg class="feather-art" viewBox="0 0 64 64" fill="none">
              
              <path d="M 14 54 C 26 40 42 22 52 10" stroke="#f59e0b" stroke-width="2.5" stroke-linecap="round"/>
              
              <path d="M 50 12 C 40 16 28 26 22 42 C 28 38 36 34 46 22 Z" fill="#38bdf8" fill-opacity="0.9"/>
              
              <path d="M 52 10 C 46 22 38 34 26 46 C 34 44 44 38 52 24 Z" fill="#0ea5e9"/>
              
              <path d="M 14 54 L 10 58" stroke="#d97706" stroke-width="2.5" stroke-linecap="round"/>
            </svg>
          </div>
          
          
          <svg class="hand-svg" viewBox="0 0 120 70" fill="none">
            
            <path d="M 0 46 C 20 45 35 43 48 38 L 48 64 C 30 65 15 65 0 62 Z" fill="#fcd34d"/>
            <path d="M 0 46 C 20 45 35 43 48 38" stroke="#f59e0b" stroke-width="2" stroke-linecap="round"/>
            <path d="M 0 62 C 15 65 30 65 48 64" stroke="#f59e0b" stroke-width="2" stroke-linecap="round"/>
            
            <path d="M 45 38 C 55 34 72 32 86 35 C 96 38 104 45 98 55 C 92 63 75 64 48 64 Z" fill="#fde68a" stroke="#f59e0b" stroke-width="2"/>
            
            
            <path d="M 82 36 C 88 33 98 35 101 40 C 103 44 98 47 92 46" fill="#fcd34d" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 85 34 C 92 31 103 33 106 38 C 108 42 102 45 95 44" fill="#fde68a" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 84 33 C 92 28 105 30 108 35 C 110 39 104 43 96 42" fill="#fcd34d" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 80 32 C 86 26 99 26 103 31 C 105 35 98 39 90 39" fill="#fde68a" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 52 37 C 56 26 68 26 73 32 C 76 36 70 42 60 41 Z" fill="#fde68a" stroke="#f59e0b" stroke-width="2"/>
            
            <path d="M 62 45 C 72 47 80 52 82 56" stroke="#f59e0b" stroke-width="1.5" stroke-linecap="round"/>
          </svg>
        </div>
        
        <div class="level-note light-note"><span>Stays high up</span> <span>⇡</span></div>
      </div>

      
      <div class="hand-card heavy" id="card-heavy" onclick="highlightCard('heavy')">
        <div class="badge badge-heavy">Heavier 🪨</div>

        
        <div class="indicator-box">
          <svg class="arrow-down-icon" width="40" height="20" viewBox="0 0 40 20" fill="none">
            <path d="M 14 4 L 14 15 M 10 11 L 14 16 L 18 11" stroke="#334155" stroke-width="2.2" stroke-linecap="round" stroke-linejoin="round"/>
            <path d="M 26 4 L 26 15 M 22 11 L 26 16 L 30 11" stroke="#64748b" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"/>
          </svg>
        </div>

        <div class="visual-stack">
          
          <div class="item-holder">
            <svg class="rock-art" viewBox="0 0 64 64" fill="none">
              
              <path d="M 12 38 C 10 28 20 18 34 16 C 48 14 56 24 54 36 C 52 46 42 50 28 50 C 18 50 14 44 12 38 Z" fill="#475569" stroke="#334155" stroke-width="2.5"/>
              
              <path d="M 22 22 C 30 18 42 18 46 24 C 40 28 32 30 22 26 Z" fill="#64748b"/>
              <path d="M 16 34 C 24 30 38 32 44 40 C 34 46 22 46 16 38 Z" fill="#334155"/>
              <circle cx="26" cy="24" r="2" fill="#94a3b8"/>
              <circle cx="38" cy="22" r="1.5" fill="#94a3b8"/>
            </svg>
          </div>
          
          
          <svg class="hand-svg" viewBox="0 0 120 70" fill="none">
            
            <path d="M 120 46 C 100 45 85 43 72 38 L 72 64 C 90 65 105 65 120 62 Z" fill="#fcd34d"/>
            <path d="M 120 46 C 100 45 85 43 72 38" stroke="#f59e0b" stroke-width="2" stroke-linecap="round"/>
            <path d="M 120 62 C 105 65 90 65 72 64" stroke="#f59e0b" stroke-width="2" stroke-linecap="round"/>
            
            <path d="M 75 38 C 65 34 48 32 34 35 C 24 38 16 45 22 55 C 28 63 45 64 72 64 Z" fill="#fde68a" stroke="#f59e0b" stroke-width="2"/>
            
            
            <path d="M 38 36 C 32 33 22 35 19 40 C 17 44 22 47 28 46" fill="#fcd34d" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 35 34 C 28 31 17 33 14 38 C 12 42 18 45 25 44" fill="#fde68a" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 36 33 C 28 28 15 30 12 35 C 10 39 16 43 24 42" fill="#fcd34d" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 40 32 C 34 26 21 26 17 31 C 15 35 22 39 30 39" fill="#fde68a" stroke="#f59e0b" stroke-width="1.8"/>
            
            <path d="M 68 37 C 64 26 52 26 47 32 C 44 36 50 42 60 41 Z" fill="#fde68a" stroke="#f59e0b" stroke-width="2"/>
            
            <path d="M 58 45 C 48 47 40 52 38 56" stroke="#f59e0b" stroke-width="1.5" stroke-linecap="round"/>
          </svg>
        </div>

        <div class="level-note heavy-note"><span>Pulls hand down</span> <span>⇣</span></div>
      </div>
    </div>

    
    <div class="fun-tip" id="feedback-text">
      💡 Tip: Feathers float in the air, but heavy rocks sink right down!
    </div>
  </div>

  <script>
    function highlightCard(type) {
      const feedback = document.getElementById('feedback-text');
      if (type === 'light') {
        feedback.innerHTML = '🪶 <strong>Feather:</strong> Light items need very little effort to hold up!';
        feedback.style.background = '#e0f2fe';
        feedback.style.borderColor = '#7dd3fc';
        feedback.style.color = '#0369a1';
      } else {
        feedback.innerHTML = '🪨 <strong>Rock:</strong> Heavy items pull down towards the ground!';
        feedback.style.background = '#f1f5f9';
        feedback.style.borderColor = '#cbd5e1';
        feedback.style.color = '#334155';
      }
    }
  </script>
</body>
</html>

OGS.0.PS.1

Aligned learning resources

Related diagrams