<!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">
  <title>Regrouping Across Place Values</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; }
    body {
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 16px;
      user-select: none;
    }

    .header-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: 480px;
      margin-bottom: 8px;
    }

    .title {
      font-size: 15px;
      font-weight: 700;
      color: #1e2945;
    }

    .step-pill {
      background: #f1f5f9;
      color: #0284c7;
      font-size: 12px;
      font-weight: 700;
      padding: 4px 10px;
      border-radius: 12px;
    }

    /* Diagram Stage */
    .stage {
      position: relative;
      width: 100%;
      max-width: 480px;
      height: 240px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
    }

    /* Regrouping curved arrow overlay */
    .regroup-svg {
      position: absolute;
      top: 10px;
      left: 0;
      width: 100%;
      height: 90px;
      pointer-events: none;
      z-index: 10;
    }

    .regroup-path {
      fill: none;
      stroke: #0284c7;
      stroke-width: 3.5;
      stroke-linecap: round;
      stroke-dasharray: 6 6;
      opacity: 0;
      transition: opacity 0.4s ease, stroke-dashoffset 0.8s linear;
    }

    .regroup-path.active {
      opacity: 1;
      animation: dash 1.5s linear infinite;
    }

    @keyframes dash {
      to { stroke-dashoffset: -24; }
    }

    .regroup-text {
      font-size: 12px;
      font-weight: 700;
      fill: #0284c7;
      opacity: 0;
      transition: opacity 0.3s ease;
    }

    .regroup-text.active {
      opacity: 1;
    }

    /* Place Value Grid */
    .pv-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 12px;
      width: 100%;
      max-width: 400px;
      margin-top: 30px;
      z-index: 2;
    }

    .pv-box {
      background: #f8fafc;
      border: 2px solid #e2e8f0;
      border-radius: 16px;
      padding: 10px 6px;
      text-align: center;
      transition: border-color 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
      position: relative;
    }

    .pv-box.hundreds.highlight {
      border-color: #3b82f6;
      background: #eff6ff;
      box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
    }

    .pv-box.tens.highlight {
      border-color: #f59e0b;
      background: #fffbeb;
      box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.2);
    }

    .pv-box.ones.highlight {
      border-color: #10b981;
      background: #ecfdf5;
      box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.2);
    }

    .pv-name {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #64748b;
      margin-bottom: 4px;
    }

    .pv-digit {
      font-size: 38px;
      font-weight: 800;
      line-height: 1;
      color: #1e2945;
      transition: color 0.3s ease, transform 0.3s ease;
    }

    .pv-sub {
      font-size: 12px;
      font-weight: 700;
      height: 18px;
      margin-top: 6px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    /* Floating annotations */
    .note-badge {
      position: absolute;
      bottom: 6px;
      font-size: 13px;
      font-weight: 700;
      padding: 6px 14px;
      border-radius: 20px;
      background: #1e2945;
      color: #ffffff;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: all 0.3s ease;
      box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    }

    /* Controls */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 12px;
      width: 100%;
      max-width: 480px;
      margin-top: 10px;
    }

    .btn {
      background: #f1f5f9;
      border: none;
      color: #1e2945;
      font-size: 13px;
      font-weight: 600;
      padding: 8px 16px;
      border-radius: 8px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background 0.2s;
    }

    .btn:hover {
      background: #e2e8f0;
    }

    .btn-primary {
      background: #0284c7;
      color: #ffffff;
    }

    .btn-primary:hover {
      background: #0369a1;
    }

    .dots {
      display: flex;
      gap: 6px;
    }

    .dot {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: #cbd5e1;
      cursor: pointer;
      transition: background 0.2s;
    }

    .dot.active {
      background: #0284c7;
      width: 18px;
      border-radius: 4px;
    }
  </style>
</head>
<body>

  <div class="header-bar">
    <span class="title">Rounding 698 to Nearest 10</span>
    <span class="step-pill" id="stepPill">Step 1 of 4</span>
  </div>

  <div class="stage">
    
    <svg class="regroup-svg" viewBox="0 0 400 90">
      <defs>
        <marker id="arrowhead" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#0284c7" />
        </marker>
      </defs>
      <path id="regroupPath" class="regroup-path" d="M 200 48 C 200 10, 68 10, 68 42" marker-end="url(#arrowhead)"></path>
      <text id="regroupLabel" class="regroup-text" x="134" y="24" text-anchor="middle">10 tens = 1 hundred</text>
    </svg>

    
    <div class="pv-grid">
      
      <div class="pv-box hundreds" id="boxH">
        <div class="pv-name">Hundreds</div>
        <div class="pv-digit" id="digitH">6</div>
        <div class="pv-sub" id="subH" style="color: #2563eb;"></div>
      </div>

      
      <div class="pv-box tens" id="boxT">
        <div class="pv-name">Tens</div>
        <div class="pv-digit" id="digitT">9</div>
        <div class="pv-sub" id="subT" style="color: #d97706;"></div>
      </div>

      
      <div class="pv-box ones" id="boxO">
        <div class="pv-name">Ones</div>
        <div class="pv-digit" id="digitO">8</div>
        <div class="pv-sub" id="subO" style="color: #059669;"></div>
      </div>
    </div>

    
    <div class="note-badge" id="badge">
      <span>Start with 698</span>
    </div>
  </div>

  
  <div class="controls">
    <button class="btn" id="prevBtn">← Back</button>
    <div class="dots" id="dotsContainer">
      <div class="dot active"></div>
      <div class="dot"></div>
      <div class="dot"></div>
      <div class="dot"></div>
    </div>
    <button class="btn btn-primary" id="nextBtn">Next →</button>
  </div>

  <script>
    const steps = [
      {
        pill: "Step 1: Check Ones",
        h: "6", t: "9", o: "8",
        subH: "", subT: "", subO: "",
        hH: false, hT: false, hO: true,
        regroup: false,
        badge: "Look at ones digit (8)"
      },
      {
        pill: "Step 2: Round Up",
        h: "6", t: "9", o: "0",
        subH: "", subT: "+1 ten", subO: "8 ≥ 5",
        hH: false, hT: true, hO: false,
        regroup: false,
        badge: "8 ≥ 5 → Round up (+1 ten)"
      },
      {
        pill: "Step 3: Regroup 10 Tens",
        h: "6", t: "10", o: "0",
        subH: "+1 hundred", subT: "10 tens", subO: "",
        hH: true, hT: true, hO: false,
        regroup: true,
        badge: "10 tens regroup into 1 hundred"
      },
      {
        pill: "Step 4: Final Result",
        h: "7", t: "0", o: "0",
        subH: "", subT: "", subO: "",
        hH: true, hT: false, hO: false,
        regroup: false,
        badge: "✓ 698 rounds to 700"
      }
    ];

    let currentStep = 0;

    const pillEl = document.getElementById('stepPill');
    const digitH = document.getElementById('digitH');
    const digitT = document.getElementById('digitT');
    const digitO = document.getElementById('digitO');
    const subH = document.getElementById('subH');
    const subT = document.getElementById('subT');
    const subO = document.getElementById('subO');
    const boxH = document.getElementById('boxH');
    const boxT = document.getElementById('boxT');
    const boxO = document.getElementById('boxO');
    const badge = document.getElementById('badge');
    const regroupPath = document.getElementById('regroupPath');
    const regroupLabel = document.getElementById('regroupLabel');
    const prevBtn = document.getElementById('prevBtn');
    const nextBtn = document.getElementById('nextBtn');
    const dots = document.querySelectorAll('.dot');

    function render(idx) {
      const s = steps[idx];
      pillEl.textContent = s.pill;
      digitH.textContent = s.h;
      digitT.textContent = s.t;
      digitO.textContent = s.o;
      subH.textContent = s.subH;
      subT.textContent = s.subT;
      subO.textContent = s.subO;

      boxH.className = 'pv-box hundreds' + (s.hH ? ' highlight' : '');
      boxT.className = 'pv-box tens' + (s.hT ? ' highlight' : '');
      boxO.className = 'pv-box ones' + (s.hO ? ' highlight' : '');

      if (s.regroup) {
        regroupPath.classList.add('active');
        regroupLabel.classList.add('active');
      } else {
        regroupPath.classList.remove('active');
        regroupLabel.classList.remove('active');
      }

      badge.innerHTML = s.badge;
      if (idx === 3) {
        badge.style.background = '#0284c7';
      } else {
        badge.style.background = '#1e2945';
      }

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

      prevBtn.disabled = (idx === 0);
      prevBtn.style.opacity = idx === 0 ? '0.4' : '1';
      nextBtn.textContent = (idx === steps.length - 1) ? 'Restart ↺' : 'Next →';
    }

    function goTo(idx) {
      currentStep = (idx + steps.length) % steps.length;
      render(currentStep);
    }

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

    nextBtn.addEventListener('click', () => {
      goTo((currentStep + 1) % steps.length);
    });

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

    render(0);
  </script>
</body>
</html>

Rounding Numbers to the Nearest 10 Within 1,000

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      min-height: 100%;
      padding: 12px 10px;
      user-select: none;
      -webkit-user-select: none;
    }

    .diagram-area {
      position: relative;
      width: 100%;
      max-width: 580px;
      aspect-ratio: 16 / 10;
    }

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

    /* Cart Element */
    #cart {
      transition: transform 0.8s cubic-bezier(0.25, 1, 0.5, 1);
      transform-origin: center;
      cursor: grab;
    }

    /* Number Picker Bar */
    .selector-bar {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 5px;
      width: 100%;
      max-width: 540px;
      margin-top: 6px;
    }

    .num-btn {
      flex: 1 0 38px;
      max-width: 46px;
      height: 34px;
      border: 1px solid #e2e8f0;
      background: #f8fafc;
      border-radius: 8px;
      font-size: 14px;
      font-weight: 700;
      color: #475569;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: background 0.2s, color 0.2s, box-shadow 0.2s;
    }

    .num-btn:hover {
      background: #e2e8f0;
    }

    .num-btn.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
      box-shadow: 0 2px 6px rgba(2, 132, 199, 0.35);
    }

    .num-btn.peak-btn {
      border-color: #38bdf8;
      background: #e0f2fe;
      color: #0369a1;
    }

    .num-btn.peak-btn.active {
      background: #0284c7;
      color: #ffffff;
    }

    /* Status Banner */
    .status-badge {
      font-size: 15px;
      font-weight: 800;
      padding: 4px 14px;
      border-radius: 20px;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      margin-top: 4px;
      background: #f1f5f9;
      color: #334155;
      transition: background 0.3s, color 0.3s;
    }
  </style>
</head>
<body>

  
  <div class="diagram-area">
    <svg viewBox="0 0 580 340">
      <defs>
        
        <linearGradient id="hillGrad" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#f1f5f9" />
          <stop offset="50%" stop-color="#e0f2fe" />
          <stop offset="100%" stop-color="#dcfce7" />
        </linearGradient>
        <linearGradient id="leftSlopeGrad" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#64748b" />
          <stop offset="100%" stop-color="#0284c7" />
        </linearGradient>
        <linearGradient id="rightSlopeGrad" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#0284c7" />
          <stop offset="100%" stop-color="#16a34a" />
        </linearGradient>
        <filter id="shadow" x="-20%" y="-20%" width="140%" height="140%">
          <feDropShadow dx="0" dy="2" stdDeviation="3" flood-opacity="0.15" />
        </filter>
      </defs>

      
      <path d="M 30 260 C 130 260, 200 80, 290 80 C 380 80, 450 260, 550 260 L 550 300 L 30 300 Z" fill="url(#hillGrad)" />
      <path d="M 30 260 C 130 260, 200 80, 290 80 C 380 80, 450 260, 550 260" fill="none" stroke="#94a3b8" stroke-width="4" stroke-linecap="round" />

      
      <path d="M 175 140 Q 110 200 70 235" fill="none" stroke="#64748b" stroke-width="3" stroke-dasharray="4 4" />
      <polygon points="62,242 76,236 71,226" fill="#64748b" />
      <text x="110" y="165" fill="#475569" font-size="14" font-weight="700" text-anchor="middle">Round Down</text>
      <text x="110" y="183" fill="#64748b" font-size="12" font-weight="600" text-anchor="middle">(0 – 4)</text>

      
      <path d="M 405 140 Q 470 200 510 235" fill="none" stroke="#16a34a" stroke-width="3" stroke-dasharray="4 4" />
      <polygon points="518,242 509,226 504,236" fill="#16a34a" />
      <text x="470" y="165" fill="#15803d" font-size="14" font-weight="700" text-anchor="middle">Round Up</text>
      <text x="470" y="183" fill="#16a34a" font-size="12" font-weight="600" text-anchor="middle">(5 – 9)</text>

      
      <g transform="translate(45, 275)">
        <rect x="-35" y="-16" width="70" height="32" rx="16" fill="#475569" filter="url(#shadow)" />
        <text x="0" y="5" fill="#ffffff" font-size="16" font-weight="800" text-anchor="middle">720</text>
      </g>
      <g transform="translate(535, 275)">
        <rect x="-35" y="-16" width="70" height="32" rx="16" fill="#16a34a" filter="url(#shadow)" />
        <text x="0" y="5" fill="#ffffff" font-size="16" font-weight="800" text-anchor="middle">730</text>
      </g>

      
       <circle cx="50" cy="258" r="4" fill="#64748b" />
       <circle cx="95" cy="240" r="4" fill="#64748b" />
       <circle cx="145" cy="205" r="4" fill="#64748b" />
       <circle cx="195" cy="155" r="4" fill="#64748b" />
       <circle cx="242" cy="108" r="4" fill="#64748b" />

      
      <g id="peakFlag" transform="translate(290, 48)">
        <line x1="0" y1="32" x2="0" y2="4" stroke="#0284c7" stroke-width="2" />
        <polygon points="0,4 28,11 0,18" fill="#0284c7" />
        <rect x="-24" y="-16" width="48" height="20" rx="6" fill="#0284c7" />
        <text x="0" y="-2" fill="#ffffff" font-size="12" font-weight="800" text-anchor="middle">725</text>
      </g>
      <circle cx="290" cy="80" r="5" fill="#0284c7" />

       <circle cx="338" cy="108" r="4" fill="#16a34a" />
       <circle cx="385" cy="155" r="4" fill="#16a34a" />
       <circle cx="435" cy="205" r="4" fill="#16a34a" />
       <circle cx="485" cy="240" r="4" fill="#16a34a" />
       <circle cx="530" cy="258" r="4" fill="#16a34a" />

      
      <g id="cart" transform="translate(290, 80)">
        <g transform="translate(0, -22)">
          
          <rect x="-22" y="-14" width="44" height="24" rx="6" fill="#0284c7" filter="url(#shadow)" />
          <text id="cartLabel" x="0" y="3" fill="#ffffff" font-size="13" font-weight="800" text-anchor="middle">725</text>
          
          <circle cx="-13" cy="11" r="5" fill="#1e2945" stroke="#ffffff" stroke-width="1.5" />
          <circle cx="13" cy="11" r="5" fill="#1e2945" stroke="#ffffff" stroke-width="1.5" />
          
          <text id="cartArrow" x="18" y="-14" font-size="12">👉</text>
        </g>
      </g>
    </svg>
  </div>

  
  <div id="statusBadge" class="status-badge">
    725 rounds up to 730
  </div>

  
  <div class="selector-bar">
    <button class="num-btn" data-num="720">720</button>
    <button class="num-btn" data-num="721">721</button>
    <button class="num-btn" data-num="722">722</button>
    <button class="num-btn" data-num="723">723</button>
    <button class="num-btn" data-num="724">724</button>
    <button class="num-btn peak-btn active" data-num="725">725</button>
    <button class="num-btn" data-num="726">726</button>
    <button class="num-btn" data-num="727">727</button>
    <button class="num-btn" data-num="728">728</button>
    <button class="num-btn" data-num="729">729</button>
    <button class="num-btn" data-num="730">730</button>
  </div>

  <script>
    // Coordinates for each number position on the hill
    const coords = {
      720: { x: 50,  y: 258, target: 720 },
      721: { x: 95,  y: 240, target: 720 },
      722: { x: 145, y: 205, target: 720 },
      723: { x: 195, y: 155, target: 720 },
      724: { x: 242, y: 108, target: 720 },
      725: { x: 290, y: 80,  target: 730 }, // 725 rolls RIGHT to 730!
      726: { x: 338, y: 108, target: 730 },
      727: { x: 385, y: 155, target: 730 },
      728: { x: 435, y: 205, target: 730 },
      729: { x: 485, y: 240, target: 730 },
      730: { x: 530, y: 258, target: 730 }
    };

    const cart = document.getElementById('cart');
    const cartLabel = document.getElementById('cartLabel');
    const cartArrow = document.getElementById('cartArrow');
    const statusBadge = document.getElementById('statusBadge');
    const buttons = document.querySelectorAll('.num-btn');

    let rollTimeout = null;

    function selectNumber(num) {
      clearTimeout(rollTimeout);

      buttons.forEach(btn => {
        btn.classList.toggle('active', parseInt(btn.dataset.num) === num);
      });

      const pos = coords[num];
      cartLabel.textContent = num;
      cartArrow.textContent = pos.target === 730 ? '👉' : '👈';

      // 1. Place cart at the selected number position on the slope
      cart.style.transition = 'transform 0.3s cubic-bezier(0.2, 0.8, 0.4, 1)';
      cart.style.transform = `translate(${pos.x}px, ${pos.y}px)`;

      // Update badge
      if (num === 720 || num === 730) {
        statusBadge.textContent = `${num} is already a 10`;
        statusBadge.style.background = '#f1f5f9';
        statusBadge.style.color = '#334155';
      } else if (pos.target === 730) {
        statusBadge.textContent = `${num} rounds up to 730`;
        statusBadge.style.background = '#dcfce7';
        statusBadge.style.color = '#15803d';
      } else {
        statusBadge.textContent = `${num} rounds down to 720`;
        statusBadge.style.background = '#f1f5f9';
        statusBadge.style.color = '#475569';
      }

      // 2. Animate rolling down towards the target nearest ten
      rollTimeout = setTimeout(() => {
        const dest = coords[pos.target];
        cart.style.transition = 'transform 0.9s cubic-bezier(0.45, 0.05, 0.55, 0.95)';
        cart.style.transform = `translate(${dest.x}px, ${dest.y}px)`;
      }, 450);
    }

    // Attach click handlers
    buttons.forEach(btn => {
      btn.addEventListener('click', () => {
        selectNumber(parseInt(btn.dataset.num));
      });
    });

    // Initial state: Start at 725 and roll down to 730
    selectNumber(725);
  </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">
  <title>Rounding to the Nearest 10</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    }

    body {
      background: #f8fafc;
      color: #1e293b;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    /* Top Controls Bar */
    .controls-bar {
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
      background: #ffffff;
      padding: 6px 10px;
      border-radius: 10px;
      border: 1px solid #e2e8f0;
    }

    .step-buttons {
      display: flex;
      flex-wrap: wrap;
      gap: 6px;
    }

    .btn-step {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      color: #475569;
      padding: 5px 10px;
      border-radius: 6px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      transition: background 0.2s, color 0.2s, border-color 0.2s;
    }

    .btn-step.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #1d4ed8;
      box-shadow: 0 1px 3px rgba(37, 99, 235, 0.3);
    }

    .btn-play {
      background: #0f172a;
      color: #ffffff;
      border: none;
      padding: 5px 12px;
      border-radius: 6px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    /* Main Comparison Grid */
    .grid-container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
    }

    @media (max-width: 540px) {
      .grid-container {
        grid-template-columns: 1fr;
      }
    }

    /* Panel Cards */
    .panel-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
      box-shadow: 0 1px 3px rgba(0,0,0,0.03);
    }

    .panel-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      border-bottom: 1px solid #f1f5f9;
      padding-bottom: 6px;
    }

    .panel-title {
      font-size: 14px;
      font-weight: 700;
      color: #334155;
    }

    .type-tag {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      padding: 2px 6px;
      border-radius: 4px;
      letter-spacing: 0.5px;
    }

    .tag-down { background: #dbeafe; color: #1e40af; }
    .tag-up { background: #d1fae5; color: #065f46; }

    /* Number Callout Area */
    .num-display-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
    }

    .big-number {
      font-size: 28px;
      font-weight: 800;
      letter-spacing: 1px;
      display: flex;
      align-items: center;
      color: #1e293b;
    }

    .digit-box {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 0 4px;
      margin-left: 2px;
      border-radius: 6px;
      transition: all 0.3s ease;
      border: 2px solid transparent;
    }

    .digit-box.highlight-blue {
      background: #eff6ff;
      border-color: #3b82f6;
      color: #1d4ed8;
      box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
    }

    .digit-box.highlight-green {
      background: #ecfdf5;
      border-color: #10b981;
      color: #047857;
      box-shadow: 0 0 0 2px rgba(16, 185, 129, 0.2);
    }

    .rule-badge {
      font-size: 12px;
      font-weight: 700;
      padding: 4px 8px;
      border-radius: 20px;
      opacity: 0.2;
      transition: opacity 0.3s ease, transform 0.3s ease;
      transform: translateY(2px);
    }

    .rule-badge.visible {
      opacity: 1;
      transform: translateY(0);
    }

    .rule-blue { background: #eff6ff; color: #1d4ed8; border: 1px solid #bfdbfe; }
    .rule-green { background: #ecfdf5; color: #047857; border: 1px solid #a7f3d0; }

    /* SVG Number Line Container */
    .svg-container {
      width: 100%;
      height: 105px;
      position: relative;
    }

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

    /* Result Banner */
    .result-banner {
      border-radius: 8px;
      padding: 8px 10px;
      font-size: 13px;
      font-weight: 700;
      display: flex;
      align-items: center;
      justify-content: space-between;
      opacity: 0.25;
      transition: opacity 0.3s ease;
    }

    .result-banner.visible {
      opacity: 1;
    }

    .banner-blue {
      background: #eff6ff;
      border: 1px solid #bfdbfe;
      color: #1e40af;
    }

    .banner-green {
      background: #ecfdf5;
      border: 1px solid #a7f3d0;
      color: #065f46;
    }

    .extra-note {
      font-size: 11px;
      font-weight: 600;
      color: #059669;
    }
  </style>
</head>
<body>

  
  <div class="controls-bar">
    <div class="step-buttons">
      <button class="btn-step active" id="stepBtn0" onclick="setStep(0)">1. Look at Ones</button>
      <button class="btn-step" id="stepBtn1" onclick="setStep(1)">2. Compare Midpoint</button>
      <button class="btn-step" id="stepBtn2" onclick="setStep(2)">3. Round to 10</button>
    </div>
    <button class="btn-play" id="playBtn" onclick="togglePlay()">
      <span id="playIcon">⏸</span> <span id="playText">Pause</span>
    </button>
  </div>

  
  <div class="grid-container">
    
    
    <div class="panel-card">
      <div class="panel-header">
        <span class="panel-title">Example 1: 583</span>
        <span class="type-tag tag-down">Round Down</span>
      </div>

      <div class="num-display-row">
        <div class="big-number">
          58<span class="digit-box highlight-blue" id="digit3">3</span>
        </div>
        <div class="rule-badge rule-blue" id="ruleLeft">
          3 &lt; 5 → Round Down
        </div>
      </div>

      <div class="svg-container">
        <svg viewBox="0 0 300 100">
          <defs>
            <marker id="arrowBlue" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
              <polygon points="6 0, 0 3, 6 6" fill="#2563eb" />
            </marker>
          </defs>

          
          <line x1="25" y1="65" x2="275" y2="65" stroke="#94a3b8" stroke-width="2" stroke-linecap="round" />

          
           <line x1="30" y1="58" x2="30" y2="72" stroke="#475569" stroke-width="2.5" />
           <line x1="54" y1="61" x2="54" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="78" y1="61" x2="78" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="102" y1="61" x2="102" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="126" y1="61" x2="126" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="150" y1="56" x2="150" y2="74" stroke="#d97706" stroke-width="2" stroke-dasharray="3,2" />
           <line x1="174" y1="61" x2="174" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="198" y1="61" x2="198" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="222" y1="61" x2="222" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="246" y1="61" x2="246" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="270" y1="58" x2="270" y2="72" stroke="#475569" stroke-width="2.5" />

          
          <text x="30" y="87" text-anchor="middle" font-size="12" font-weight="700" fill="#1e293b">580</text>
          <text x="270" y="87" text-anchor="middle" font-size="12" font-weight="700" fill="#64748b">590</text>

          
          <g id="midpointLeft" style="transition: opacity 0.3s ease; opacity: 0.3;">
            <line x1="150" y1="26" x2="150" y2="56" stroke="#d97706" stroke-width="1.5" stroke-dasharray="2,2" />
            <rect x="115" y="10" width="70" height="16" rx="4" fill="#fef3c7" stroke="#f59e0b" stroke-width="1" />
            <text x="150" y="22" text-anchor="middle" font-size="10" font-weight="700" fill="#92400e">Midpoint 585</text>
          </g>

          
          <path id="swoopLeft" d="M 102 52 Q 66 22 34 56" fill="none" stroke="#2563eb" stroke-width="2.5" stroke-linecap="round" marker-end="url(#arrowBlue)" style="transition: opacity 0.3s ease; opacity: 0;" />

          
          <circle cx="102" cy="65" r="5.5" fill="#2563eb" stroke="#ffffff" stroke-width="2" />
          <text x="102" y="47" text-anchor="middle" font-size="11" font-weight="800" fill="#1d4ed8">583</text>
        </svg>
      </div>

      <div class="result-banner banner-blue" id="bannerLeft">
        <span>583 → 580</span>
        <span style="font-size:11px; font-weight:600;">Nearest 10</span>
      </div>
    </div>

    
    <div class="panel-card">
      <div class="panel-header">
        <span class="panel-title">Example 2: 497</span>
        <span class="type-tag tag-up">Round Up</span>
      </div>

      <div class="num-display-row">
        <div class="big-number">
          49<span class="digit-box highlight-green" id="digit7">7</span>
        </div>
        <div class="rule-badge rule-green" id="ruleRight">
          7 ≥ 5 → Round Up
        </div>
      </div>

      <div class="svg-container">
        <svg viewBox="0 0 300 100">
          <defs>
            <marker id="arrowGreen" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
              <polygon points="0 0, 6 3, 0 6" fill="#10b981" />
            </marker>
          </defs>

          
          <line x1="25" y1="65" x2="275" y2="65" stroke="#94a3b8" stroke-width="2" stroke-linecap="round" />

          
           <line x1="30" y1="58" x2="30" y2="72" stroke="#64748b" stroke-width="2.5" />
           <line x1="54" y1="61" x2="54" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="78" y1="61" x2="78" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="102" y1="61" x2="102" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="126" y1="61" x2="126" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="150" y1="56" x2="150" y2="74" stroke="#d97706" stroke-width="2" stroke-dasharray="3,2" />
           <line x1="174" y1="61" x2="174" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="198" y1="61" x2="198" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="222" y1="61" x2="222" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="246" y1="61" x2="246" y2="69" stroke="#cbd5e1" stroke-width="1.5" />
           <line x1="270" y1="58" x2="270" y2="72" stroke="#047857" stroke-width="2.5" />

          
          <text x="30" y="87" text-anchor="middle" font-size="12" font-weight="700" fill="#64748b">490</text>
          <text x="270" y="87" text-anchor="middle" font-size="12" font-weight="700" fill="#047857">500</text>

          
          <g id="midpointRight" style="transition: opacity 0.3s ease; opacity: 0.3;">
            <line x1="150" y1="26" x2="150" y2="56" stroke="#d97706" stroke-width="1.5" stroke-dasharray="2,2" />
            <rect x="115" y="10" width="70" height="16" rx="4" fill="#fef3c7" stroke="#f59e0b" stroke-width="1" />
            <text x="150" y="22" text-anchor="middle" font-size="10" font-weight="700" fill="#92400e">Midpoint 495</text>
          </g>

          
          <path id="swoopRight" d="M 198 52 Q 234 22 266 56" fill="none" stroke="#10b981" stroke-width="2.5" stroke-linecap="round" marker-end="url(#arrowGreen)" style="transition: opacity 0.3s ease; opacity: 0;" />

          
          <circle cx="198" cy="65" r="5.5" fill="#10b981" stroke="#ffffff" stroke-width="2" />
          <text x="198" y="47" text-anchor="middle" font-size="11" font-weight="800" fill="#047857">497</text>
        </svg>
      </div>

      <div class="result-banner banner-green" id="bannerRight">
        <span>497 → 500</span>
        <span class="extra-note">49 tens + 1 = 50 tens</span>
      </div>
    </div>

  </div>

  <script>
    let currentStep = 0;
    let isPlaying = true;
    let timer = null;
    const STEP_DURATION = 3500;

    function updateView() {
      // Step buttons
      for (let i = 0; i < 3; i++) {
        const btn = document.getElementById('stepBtn' + i);
        if (i === currentStep) {
          btn.classList.add('active');
        } else {
          btn.classList.remove('active');
        }
      }

      // Step 1: Identify Ones Digit
      const digit3 = document.getElementById('digit3');
      const digit7 = document.getElementById('digit7');

      // Step 2: Compare to Midpoint
      const ruleLeft = document.getElementById('ruleLeft');
      const ruleRight = document.getElementById('ruleRight');
      const midLeft = document.getElementById('midpointLeft');
      const midRight = document.getElementById('midpointRight');

      // Step 3: Round & Movement
      const swoopLeft = document.getElementById('swoopLeft');
      const swoopRight = document.getElementById('swoopRight');
      const bannerLeft = document.getElementById('bannerLeft');
      const bannerRight = document.getElementById('bannerRight');

      if (currentStep === 0) {
        digit3.classList.add('highlight-blue');
        digit7.classList.add('highlight-green');

        ruleLeft.classList.remove('visible');
        ruleRight.classList.remove('visible');
        midLeft.style.opacity = "0.2";
        midRight.style.opacity = "0.2";

        swoopLeft.style.opacity = "0";
        swoopRight.style.opacity = "0";
        bannerLeft.classList.remove('visible');
        bannerRight.classList.remove('visible');
      } else if (currentStep === 1) {
        digit3.classList.add('highlight-blue');
        digit7.classList.add('highlight-green');

        ruleLeft.classList.add('visible');
        ruleRight.classList.add('visible');
        midLeft.style.opacity = "1";
        midRight.style.opacity = "1";

        swoopLeft.style.opacity = "0";
        swoopRight.style.opacity = "0";
        bannerLeft.classList.remove('visible');
        bannerRight.classList.remove('visible');
      } else if (currentStep === 2) {
        digit3.classList.add('highlight-blue');
        digit7.classList.add('highlight-green');

        ruleLeft.classList.add('visible');
        ruleRight.classList.add('visible');
        midLeft.style.opacity = "0.6";
        midRight.style.opacity = "0.6";

        swoopLeft.style.opacity = "1";
        swoopRight.style.opacity = "1";
        bannerLeft.classList.add('visible');
        bannerRight.classList.add('visible');
      }
    }

    function setStep(idx) {
      currentStep = idx;
      updateView();
      if (isPlaying) {
        resetTimer();
      }
    }

    function nextStep() {
      currentStep = (currentStep + 1) % 3;
      updateView();
    }

    function resetTimer() {
      if (timer) clearInterval(timer);
      timer = setInterval(nextStep, STEP_DURATION);
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      const playIcon = document.getElementById('playIcon');
      const playText = document.getElementById('playText');
      if (isPlaying) {
        playIcon.textContent = '⏸';
        playText.textContent = 'Pause';
        resetTimer();
      } else {
        playIcon.textContent = '▶';
        playText.textContent = 'Play';
        if (timer) clearInterval(timer);
      }
    }

    // Initialize
    updateView();
    resetTimer();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 12px;
      min-height: 100%;
    }
    .wrapper {
      width: 100%;
      max-width: 640px;
      display: flex;
      flex-direction: column;
      gap: 14px;
    }
    .badges-row {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
      padding: 0 10px;
    }
    .badge {
      font-size: 13px;
      font-weight: 700;
      padding: 6px 12px;
      border-radius: 20px;
      display: flex;
      align-items: center;
      gap: 6px;
      letter-spacing: -0.2px;
    }
    .badge-lower {
      background: #fee2e2;
      color: #991b1b;
      border: 1px solid #fecaca;
    }
    .badge-upper {
      background: #dcfce7;
      color: #166534;
      border: 1px solid #bbf7d0;
    }
    .svg-container {
      width: 100%;
      position: relative;
    }
    svg {
      width: 100%;
      height: auto;
      display: block;
      overflow: visible;
    }
    .result-card {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px 16px;
      text-align: center;
      font-size: 14px;
      font-weight: 600;
      color: #1e2945;
    }
    .highlight-green {
      color: #16a34a;
      font-weight: 700;
    }
    .highlight-red {
      color: #dc2626;
      font-weight: 700;
    }
    .highlight-blue {
      color: #0284c7;
      font-weight: 700;
    }
    .tick-hitbox {
      cursor: pointer;
    }
    .tick-hitbox:hover text {
      fill: #0284c7;
      font-weight: bold;
    }
  </style>
</head>
<body>

<div class="wrapper">
  
  <div class="badges-row">
    <div class="badge badge-lower">
      <span>◀ Lower 10: <strong>340</strong></span>
    </div>
    <div class="badge badge-upper">
      <span>Upper 10: <strong>350</strong> ▶</span>
    </div>
  </div>

  
  <div class="svg-container">
    <svg viewBox="0 0 600 200" id="numlineSvg">
      <defs>
        
        <marker id="arrow-red" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#ef4444" />
        </marker>
        <marker id="arrow-green" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#16a34a" />
        </marker>
        
        <filter id="pin-shadow" x="-30%" y="-30%" width="160%" height="160%">
          <feDropShadow dx="0" dy="2" stdDeviation="2" flood-color="#0284c7" flood-opacity="0.3"/>
        </filter>
      </defs>

      
      <line x1="30" y1="130" x2="570" y2="130" stroke="#cbd5e1" stroke-width="4" stroke-linecap="round" />

      
      <path id="arcLeft" d="M 470 112 Q 260 20 50 116" fill="none" stroke="#ef4444" stroke-width="3" stroke-dasharray="6,4" marker-end="url(#arrow-red)" />
      
      
      <path id="arcRight" d="M 490 112 Q 520 62 548 116" fill="none" stroke="#16a34a" stroke-width="3.5" marker-end="url(#arrow-green)" />

      
      <g id="labelLeftGroup" transform="translate(260, 48)">
        <rect x="-42" y="-13" width="84" height="24" rx="12" fill="#fee2e2" stroke="#fca5a5" stroke-width="1"/>
        <text x="0" y="4" font-size="12" font-weight="700" fill="#dc2626" text-anchor="middle">8 away</text>
      </g>

      <g id="labelRightGroup" transform="translate(520, 68)">
        <rect x="-38" y="-13" width="76" height="24" rx="12" fill="#dcfce7" stroke="#86efac" stroke-width="1"/>
        <text x="0" y="4" font-size="12" font-weight="700" fill="#15803d" text-anchor="middle">2 away</text>
      </g>

      
      
      
      <g id="ticksGroup"></g>

      
      <g id="pinGroup" transform="translate(480, 130)">
        
        <line x1="0" y1="-32" x2="0" y2="0" stroke="#0284c7" stroke-width="2" stroke-dasharray="2,2"/>
        
        <g filter="url(#pin-shadow)" transform="translate(0, -38)">
          <path d="M 0 0 C -12 -12 -14 -22 -14 -28 A 14 14 0 0 1 14 -28 C 14 -22 12 -12 0 0 Z" fill="#0284c7"/>
          <circle cx="0" cy="-28" r="5" fill="#ffffff" />
        </g>
        <text x="0" y="-72" font-size="13" font-weight="800" fill="#0369a1" text-anchor="middle">348</text>
        <circle cx="0" cy="0" r="6" fill="#0284c7" stroke="#ffffff" stroke-width="2"/>
      </g>
    </svg>
  </div>

  
  <div class="result-card" id="explanationText">
    <span class="highlight-blue">348</span> is closer to <span class="highlight-green">350 (2 away)</span> than <span class="highlight-red">340 (8 away)</span> → <strong>Rounds to 350</strong>
  </div>
</div>

<script>
  // Generate accurate ticks from 340 to 350
  const ticksGroup = document.getElementById('ticksGroup');
  const startVal = 340;
  const endVal = 350;
  const startX = 50;
  const spacing = 50; // 500px total / 10 divisions

  for (let i = 0; i <= 10; i++) {
    const val = startVal + i;
    const x = startX + i * spacing;
    const isEndpoint = (i === 0 || i === 10);
    const isMidpoint = (i === 5);
    const isTarget = (val === 348);

    const g = document.createElementNS('http://www.w3.org/2000/svg', 'g');
    g.setAttribute('class', 'tick-hitbox');

    // Tick line
    const line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
    const tickHeight = isEndpoint ? 16 : (isMidpoint ? 12 : 8);
    line.setAttribute('x1', x);
    line.setAttribute('y1', 130 - tickHeight);
    line.setAttribute('x2', x);
    line.setAttribute('y2', 130 + tickHeight);
    line.setAttribute('stroke', isEndpoint ? '#1e2945' : (isTarget ? '#0284c7' : '#94a3b8'));
    line.setAttribute('stroke-width', isEndpoint ? '3' : (isTarget ? '3' : '2'));

    // Tick label
    const text = document.createElementNS('http://www.w3.org/2000/svg', 'text');
    text.setAttribute('x', x);
    text.setAttribute('y', 162);
    text.setAttribute('text-anchor', 'middle');
    text.setAttribute('font-size', isEndpoint ? '15' : '13');
    text.setAttribute('font-weight', isEndpoint || isTarget ? '700' : '500');
    text.setAttribute('fill', isEndpoint ? '#0f172a' : (isTarget ? '#0284c7' : '#64748b'));
    text.textContent = val;

    g.appendChild(line);
    g.appendChild(text);
    ticksGroup.appendChild(g);
  }
</script>

</body>
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Counting Hundreds, Tens and Ones with Base-Ten Blocks

Building Three-Digit Numbers with Hundreds, Tens and Ones

Partitioning Three-Digit Numbers into Hundreds, Tens and Ones

Flexible Partitioning of Three-Digit Numbers

Reading and Writing Three-Digit Numbers

Writing Three-Digit Numbers in Words

Locating Three-Digit Numbers on Open Number Lines

Comparing Three-Digit Numbers Using Place Value

Ordering Sets of Three-Digit Numbers

Solving Place Value and Number Puzzles to 1,000

math

Place Value and Representing Numbers to 1,000

Comparación y orden de números grandes

Redondeo a la decena, centena y unidad de mil más cercana

Redondeo a la decena de mil, centena de mil y millón más cercano

Estimación en contextos cotidianos y censales

Patrones numéricos en la recta numérica hasta el millón

Análisis de errores comunes en el valor posicional

Regularidades del sistema decimal comparado con otros sistemas

Resolución de desafíos de lógica con cifras y posiciones

Comparación, redondeo y aplicaciones del valor posicional

Finding 10 More and 10 Less Than a Three-Digit Number

Finding 100 More and 100 Less Than a Three-Digit Number

Counting Forwards and Backwards in Fifties to 1,000

Counting Forwards and Backwards in Hundreds to 1,000

Counting in Multiples of 4 from Zero

Counting in Multiples of 8 from Zero

Estimating Quantities and Positions up to 1,000

Solving Missing Number Sequence Problems to 1,000

Solving Real-World Three-Digit Number Problems

Number Sequences, Multiples and Estimation to 1,000

How Digits Shift Across Place Values to 100,000

Describing Place Value Relationships Through Hundred-Thousands

Locating Numbers on Number Lines to 100,000

Rounding to the Nearest Ten Using Number Lines

Rounding to the Nearest Hundred Using Number Lines

Rounding to the Nearest Thousand Using Number Lines

Rounding to the Nearest Ten-Thousand Using Number Lines

Using Words to Describe Relative Size for Rounding

Rounding to Different Place Values: Mixed Practice

Place Value Patterns and Rounding to 100,000

Algoritmo estándar de la suma con múltiples reagrupaciones

Propiedades conmutativa y asociativa en el cálculo mental

Algoritmo estándar de la resta con desagrupación continua

Resta atravesando ceros: estrategias y procedimientos

Estimación de sumas y diferencias para verificar resultados

Relación inversa entre suma y resta para comprobar operaciones

Algoritmos y estrategias de cálculo de suma y resta

Comparing Numbers to 100,000

Ordering Numbers to 100,000

Using >, <, and = Symbols with Numbers to 100,000

Place Value Word Problems to 100,000

Choosing Tools for Place Value Problems

Patterns in Place Value to 100,000

Reading Number Lines with Different Scales

Comparing and Ordering on Number Lines to 100,000

Place Value in the Real World

Comparing, Ordering, and Applying Numbers to 100,000

Adding Ones to a Three-Digit Number Without Bridging

Adding Ones to a Three-Digit Number Crossing Tens

Subtracting Ones from a Three-Digit Number Without Bridging

Subtracting Ones from a Three-Digit Number Crossing Tens

Adding Multiples of Ten to a Three-Digit Number Without Bridging

Adding Multiples of Ten to a Three-Digit Number Crossing Hundreds

Subtracting Multiples of Ten from a Three-Digit Number

Mentally Adding Hundreds to Three-Digit Numbers

Mentally Subtracting Hundreds from Three-Digit Numbers

Estimating Three-Digit Sums and Differences

Solving Mental Addition and Subtraction Word Problems

Mental Addition and Subtraction (Three-Digit Numbers)

Rzuty dziesiątek i setek

Zaokrąglanie liczb do dziesiątek

Zaokrąglanie liczb do setek i tysięcy

Szacowanie liczb w kontekście

Liczby w otoczeniu – odczytywanie i porządkowanie

Zagadki cyfrowe – logiczne zadania z liczbami

Sprawdzenie – liczby i ich własności

Rachunki pamięciowe, zaokrąglanie i zastosowania

Situaciones aditivas de composición parte-todo

Situaciones aditivas de transformación: aumento y disminución

Situaciones aditivas de comparación: cuánto más y cuánto menos

Situaciones aditivas de igualación: compensar cantidades

Resolución de problemas aditivos de dos y tres pasos

Uso de diagramas de barras para modelar problemas aditivos

Estrategias de compensación y descomposición mental

Ecuaciones aditivas simples: hallar el término desconocido

Formulación de problemas aditivos a partir de datos reales

Resolución de problemas aditivos: modelación y aplicaciones

Rounding Numbers to the Nearest 100 Within 1,000

Rounding Four-Digit Numbers to the Nearest 1,000

Rounding Five-Digit Numbers to the Nearest 10,000

Rounding Multi-Digit Numbers to Any Place

Using Compatible Numbers to Estimate Sums and Differences

Assessing the Reasonableness of Answers in Word Problems

Rounding and Estimation Strategies

Rounding to the Nearest Thousand

Rounding to the Nearest Ten Thousand

Rounding Word Problems and Estimation

Rounding Whole Numbers

Using Place Value to Add Three-Digit Numbers

Column Addition with Three-Digit Numbers (No Regrouping)

Column Addition with Three-Digit Numbers (Regrouping Ones)

Column Addition with Three-Digit Numbers (Regrouping Tens)

Adding Three-Digit Numbers (Regrouping Ones and Tens)

Using Place Value to Subtract Three-Digit Numbers

Column Subtraction with Three-Digit Numbers (No Exchange)

Column Subtraction with Three-Digit Numbers (Single Exchange)

Subtracting Three-Digit Numbers (Regrouping From Hundreds to Ones)

Using Addition to Check Subtraction Within 1,000

Written Column Addition and Subtraction

Fluidez en las tablas de multiplicar hasta el 12

Propiedad distributiva de la multiplicación sobre la suma

Modelo de áreas rectangulares para la multiplicación

Multiplicación de un número de varias cifras por una cifra

Multiplicación por múltiplos de 10, 100 y 1.000

Multiplicación de dos cifras por dos cifras: productos parciales

Algoritmo estándar de la multiplicación de dos y tres cifras

Algoritmo de la multiplicación de números naturales

Propiedades asociativa y conmutativa de la multiplicación

Multiplicación de tres o más factores

Estimación de productos mediante redondeo

Problemas multiplicativos de grupos iguales y arreglos

Problemas multiplicativos de comparación: tantas veces más

Problemas multiplicativos de combinatoria y cartesiano

Duplicar y partir a la mitad como estrategia mental

Detección y corrección de errores en la multiplicación

Problemas multiplicativos de dos pasos con dinero y cantidades

Cálculo mental y problemas multiplicativos

Estimating Sums with Rounding

Estimating Differences with Rounding

Using Compatible Numbers to Estimate Addition

Using Compatible Numbers to Estimate Subtraction

Checking Addition with Subtraction

Checking Subtraction with Addition

Estimating and Checking Three-Digit Addition and Subtraction

Multiplying Multiples of Ten by Single Digits

Multiplying Two-Digit Numbers by Partitioning (Without Regrouping)

Multiplying Two-Digit Numbers by Partitioning (With Regrouping)

Using the Grid Method to Multiply Two-Digit Numbers

Expanded Short Multiplication (Two Digits by One Digit)

Dividing Multiples of Ten by Single Digits

Dividing Two-Digit Numbers by Partitioning into Tens and Ones

Dividing Two-Digit Numbers with Remainders

Using Inverse Operations to Check Written Calculations

Solving Multiplication and Division Calculation Word Problems

Multiplication and Division: Two Digits by One Digit

Dodawanie trzech i więcej liczb

Obliczenia typu 250 + 50, 180 – 30

Własności dodawania – przemienność i łączność

Sprawdzanie dodawania odejmowaniem

Sprawdzanie odejmowania dodawaniem

Szacowanie sum i różnic

Równania z okienkiem – dodawanie i odejmowanie

Zadania tekstowe – dodawanie i odejmowanie

Sprawdzenie – dodawanie i odejmowanie

Sprawność w dodawaniu i odejmowaniu – zastosowania

Significados de la división: reparto equitativo y agrupamiento

Términos de la división y prueba de la división exacta e inexacta

División de números de varias cifras entre un dígito sin residuo

División entre un dígito con residuo y ceros en el cociente

Estimación del cociente usando múltiplos del divisor

División entre dos cifras: método de cocientes parciales

Algoritmo estándar de la división por dos cifras

Ajuste del cociente estimado cuando se pasa o queda corto

Interpretación del residuo: redondear al alza o descartar

Problemas de empaquetado, transporte y reparto con residuo

División de números naturales: algoritmos y aplicaciones

One-Step Addition Word Problems Within 1,000

One-Step Subtraction Word Problems Within 1,000

Two-Step Addition and Subtraction Word Problems

Strip Diagrams for Two-Step Addition and Subtraction Problems

Selecting the Best Addition or Subtraction Strategy

Three-Digit Addition Word Problems in Context

Three-Digit Subtraction Word Problems in Context

Checking If Your Addition or Subtraction Answer Makes Sense

Solving Addition and Subtraction Word Problems Within 1,000

Propiedad de invarianza del cociente al multiplicar o dividir ambos términos

Jerarquía de las operaciones sin signos de agrupación

Uso de paréntesis y corchetes en expresiones combinadas

Traducción entre lenguaje verbal y expresiones numéricas

Problemas verbales combinados con las cuatro operaciones

Propiedades de la división y operaciones combinadas

Adding Money Amounts

Subtracting Money Amounts

Comparing Money Amounts

Making Change from a Purchase

Money Word Problems

Money in Real-World Situations

Estimating Money Amounts

Counting Collections with Multiple Bills

Making Change from Bills

Estimating Costs at the Store

Money Operations and Real-World Problems

Szacowanie iloczynów

Równania z okienkiem – mnożenie

Równania z okienkiem – dzielenie

Zastosowanie mnożenia w zadaniach

OGM.4.NBT.3

Aligned learning resources

Related diagrams