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Tutor model

i62 💰:9.4

i52 💰:7.9

🏆 i67 💰:62.5

i70 💰:125.0

i68 💰:125.0

🏆 i66 💰:75.0

i65 💰:125.0

i63 💰:62.5

i61 💰:75.0

i60 💰:9.4

i60 💰:37.5

i58 💰:62.5

i57 💰:22.5

i57 💰:37.5

i56 💰:45.0

⚡ i55 💰:11.25

i55 💰:37.5

i54 💰:62.5

i52 💰:35.0

i51 💰:37.5

i49 💰:15.0

i49 💰:62.5

i48 💰:11.3

i47 💰:7.5

i44 💰:25.0

i43 💰:37.5

i42 💰:187.5

i40 💰:5.0

i39 💰:100.0

i38 💰:37.5

i37 💰:11.0

i36 💰:187.5

i34 💰:12.5

i33 💰:37.5

i30 💰:1.0

i29 💰:1.5

i28 💰:150.0

i23 💰:20.0

i20 💰:4.0

i18 💰:1.0

i16 💰:25.0

i13 💰:1.5

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Override for the tutor's lesson content generation calls. Auto uses the system default (Claude Sonnet 5 for lesson text, Opus 5 for diagrams).

Lesson generation model

System default

i58 💰:18.8

i31 💰:11.0

i25 💰:31.3

Tutoring abilities

Imagine you have a plate of yummy cookies. Does someone bring you **more cookies**, or does a sneaky puppy **take some away**?

Every math story tells us an action. We just need to figure out if things are being **put together** or **taken apart**.

When two groups come together to make a bigger group, we use **addition** with a plus sign ($+$).

<!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;
    color: #1e2945;
    background: #f8f9fa;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 12px;
    min-height: 100%;
    user-select: none;
    -webkit-user-select: none;
  }

  /* Mode Switcher */
  .switch-row {
    display: flex;
    gap: 8px;
    margin-bottom: 14px;
    width: 100%;
    max-width: 360px;
  }
  .tab-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 8px 12px;
    font-size: 15px;
    font-weight: 700;
    border-radius: 12px;
    border: 2px solid #e2e8f0;
    background: #ffffff;
    color: #64748b;
    cursor: pointer;
    transition: all 0.25s ease;
  }
  .tab-btn.active.add {
    background: #eff6ff;
    border-color: #2563eb;
    color: #2563eb;
    box-shadow: 0 2px 8px rgba(37, 99, 235, 0.15);
  }
  .tab-btn.active.sub {
    background: #fef2f2;
    border-color: #dc2626;
    color: #dc2626;
    box-shadow: 0 2px 8px rgba(220, 38, 38, 0.15);
  }

  /* Main Visual Stage */
  .stage-area {
    position: relative;
    width: 100%;
    max-width: 440px;
    height: 240px;
    background: #ffffff;
    border-radius: 16px;
    border: 1px solid #e2e8f0;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    padding: 16px 12px;
    overflow: hidden;
  }

  /* Groups Container */
  .groups-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    width: 100%;
    flex: 1;
  }

  .group-box {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 8px;
    border-radius: 12px;
    background: #f8fafc;
    border: 1.5px dashed #cbd5e1;
    min-width: 90px;
    transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  }

  .group-box.blue {
    background: #eff6ff;
    border-color: #93c5fd;
  }
  .group-box.emerald {
    background: #ecfdf5;
    border-color: #6ee7b7;
  }
  .group-box.combined {
    background: #f0fdf4;
    border: 2px solid #10b981;
    padding: 10px 16px;
  }

  .truck-grid {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 4px;
    min-height: 48px;
    max-width: 130px;
  }
  .truck-grid.wide {
    max-width: 260px;
  }

  .truck {
    font-size: 26px;
    line-height: 1;
    display: inline-block;
    transition: transform 0.5s ease, opacity 0.5s ease, filter 0.5s ease;
  }

  .truck.leaving {
    transform: translateY(-8px) scale(0.85);
    opacity: 0.25;
    filter: grayscale(1);
  }

  .op-symbol {
    font-size: 28px;
    font-weight: 800;
    color: #64748b;
    width: 32px;
    text-align: center;
    transition: transform 0.4s ease, color 0.4s ease;
  }
  .op-symbol.add { color: #2563eb; }
  .op-symbol.sub { color: #dc2626; }

  /* Count Badges */
  .badge {
    margin-top: 6px;
    font-size: 14px;
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 20px;
  }
  .badge.blue { background: #dbeafe; color: #1e40af; }
  .badge.emerald { background: #d1fae5; color: #065f46; }
  .badge.red { background: #fee2e2; color: #991b1b; }

  /* Equation Output Bar */
  .equation-bar {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 24px;
    font-weight: 800;
    letter-spacing: 0.5px;
    padding: 6px 16px;
    border-radius: 30px;
    background: #f1f5f9;
    color: #1e2945;
  }
  .eq-num.blue { color: #2563eb; }
  .eq-num.emerald { color: #059669; }
  .eq-num.red { color: #dc2626; }

  /* Interactive Controls */
  .controls {
    display: flex;
    gap: 10px;
    margin-top: 12px;
  }
  .action-btn {
    padding: 8px 18px;
    border-radius: 10px;
    border: none;
    font-size: 14px;
    font-weight: 700;
    cursor: pointer;
    background: #1e2945;
    color: #ffffff;
    display: flex;
    align-items: center;
    gap: 6px;
    box-shadow: 0 2px 6px rgba(0,0,0,0.1);
    transition: opacity 0.2s ease;
  }
  .action-btn:active {
    opacity: 0.85;
  }
</style>
</head>
<body>

  
  <div class="switch-row">
    <button class="tab-btn active add" id="tabAdd">➕ Join</button>
    <button class="tab-btn sub" id="tabSub">➖ Take Away</button>
  </div>

  
  <div class="stage-area" id="stage"></div>

  
  <div class="controls">
    <button class="action-btn" id="actionBtn">
      <span id="btnIcon">▶</span> <span id="btnText">Combine</span>
    </button>
  </div>

<script>
  let mode = 'add'; // 'add' or 'sub'
  let state = 0;    // 0: separated/initial, 1: combined/taken

  const stage = document.getElementById('stage');
  const tabAdd = document.getElementById('tabAdd');
  const tabSub = document.getElementById('tabSub');
  const actionBtn = document.getElementById('actionBtn');
  const btnIcon = document.getElementById('btnIcon');
  const btnText = document.getElementById('btnText');

  function render() {
    if (mode === 'add') {
      if (state === 0) {
        // Initial 2 separate groups
        stage.innerHTML = `
          <div class="groups-row">
            <div class="group-box blue">
              <div class="truck-grid">
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span><span class="truck">🚚</span>
              </div>
              <span class="badge blue">4</span>
            </div>

            <span class="op-symbol add">+</span>

            <div class="group-box emerald">
              <div class="truck-grid">
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span>
              </div>
              <span class="badge emerald">3</span>
            </div>
          </div>
          <div class="equation-bar">
            <span class="eq-num blue">4</span>
            <span>+</span>
            <span class="eq-num emerald">3</span>
            <span>=</span>
            <span>?</span>
          </div>
        `;
        btnText.textContent = 'Combine';
        btnIcon.textContent = '▶';
      } else {
        // Combined single group
        stage.innerHTML = `
          <div class="groups-row">
            <div class="group-box combined">
              <div class="truck-grid wide">
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span>
              </div>
              <span class="badge emerald">7 Trucks in all</span>
            </div>
          </div>
          <div class="equation-bar">
            <span class="eq-num blue">4</span>
            <span>+</span>
            <span class="eq-num emerald">3</span>
            <span>=</span>
            <span class="eq-num emerald">7</span>
          </div>
        `;
        btnText.textContent = 'Reset';
        btnIcon.textContent = '↺';
      }
    } else {
      // Subtraction Mode
      if (state === 0) {
        stage.innerHTML = `
          <div class="groups-row">
            <div class="group-box combined">
              <div class="truck-grid wide">
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span>
              </div>
              <span class="badge emerald">7 Total</span>
            </div>
          </div>
          <div class="equation-bar">
            <span class="eq-num emerald">7</span>
            <span>−</span>
            <span class="eq-num red">3</span>
            <span>=</span>
            <span>?</span>
          </div>
        `;
        btnText.textContent = 'Take Away';
        btnIcon.textContent = '▶';
      } else {
        // 3 taken away
        stage.innerHTML = `
          <div class="groups-row">
            <div class="group-box blue">
              <div class="truck-grid">
                <span class="truck">🚚</span><span class="truck">🚚</span>
                <span class="truck">🚚</span><span class="truck">🚚</span>
              </div>
              <span class="badge blue">4 Left</span>
            </div>

            <span class="op-symbol sub">−</span>

            <div class="group-box">
              <div class="truck-grid">
                <span class="truck leaving">🚚</span>
                <span class="truck leaving">🚚</span>
                <span class="truck leaving">🚚</span>
              </div>
              <span class="badge red">3 Away</span>
            </div>
          </div>
          <div class="equation-bar">
            <span class="eq-num emerald">7</span>
            <span>−</span>
            <span class="eq-num red">3</span>
            <span>=</span>
            <span class="eq-num blue">4</span>
          </div>
        `;
        btnText.textContent = 'Reset';
        btnIcon.textContent = '↺';
      }
    }
  }

  tabAdd.addEventListener('click', () => {
    if (mode === 'add') return;
    mode = 'add';
    state = 0;
    tabAdd.classList.add('active');
    tabSub.classList.remove('active');
    render();
  });

  tabSub.addEventListener('click', () => {
    if (mode === 'sub') return;
    mode = 'sub';
    state = 0;
    tabSub.classList.add('active');
    tabAdd.classList.remove('active');
    render();
  });

  actionBtn.addEventListener('click', () => {
    state = state === 0 ? 1 : 0;
    render();
  });

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

Let's look at this story: *Leo has 4 toy trucks. For his birthday, his aunt gives him 3 more trucks. How many trucks does Leo have in all?*

Leo starts with 4 and gets **more**. Since his group of trucks grows bigger, we add: $4 + 3 = 7$.

What happens if things fly away, get eaten, or disappear?

When items are removed or leave a group, we use **subtraction** with a minus sign ($-$) to find what is **left**.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      user-select: none;
    }
    body {
      background: #fefce8;
      color: #1e293b;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
      padding: 16px;
    }
    .main {
      width: 100%;
      max-width: 480px;
      display: flex;
      flex-direction: column;
      gap: 14px;
    }
    .toggle-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
    }
    .toggle-btn {
      border: 2px solid transparent;
      border-radius: 14px;
      padding: 10px 12px;
      font-size: 15px;
      font-weight: 700;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      background: #ffffff;
      color: #64748b;
      box-shadow: 0 2px 6px rgba(0,0,0,0.05);
      transition: all 0.25s ease;
    }
    .toggle-btn.active.sub {
      background: #ef4444;
      color: #ffffff;
      box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
    }
    .toggle-btn.active.add {
      background: #f59e0b;
      color: #ffffff;
      box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
    }
    .stage-card {
      background: #ffffff;
      border-radius: 16px;
      padding: 16px;
      box-shadow: 0 4px 16px rgba(0,0,0,0.06);
      display: flex;
      flex-direction: column;
      gap: 12px;
    }
    .pond-area {
      background: #e0f2fe;
      border: 2px dashed #7dd3fc;
      border-radius: 14px;
      padding: 16px 12px;
      min-height: 140px;
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      align-items: center;
      gap: 10px;
      position: relative;
    }
    .duck-slot {
      width: 44px;
      height: 44px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 28px;
      border-radius: 50%;
      background: #ffffff;
      box-shadow: 0 2px 5px rgba(0,0,0,0.08);
      position: relative;
      transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.4s ease, background-color 0.3s ease;
    }
    .duck-slot.leaving {
      opacity: 0.35;
      transform: translateY(-12px) scale(0.85);
      background: #fee2e2;
    }
    .duck-slot.leaving::after {
      content: '✕';
      position: absolute;
      font-size: 20px;
      font-weight: 900;
      color: #ef4444;
      line-height: 1;
    }
    .duck-slot.joining {
      background: #fef3c7;
      box-shadow: 0 0 0 3px #f59e0b;
      transform: scale(1.08);
    }
    .equation-bar {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-size: 24px;
      font-weight: 800;
      padding: 8px 12px;
      border-radius: 12px;
      background: #f8fafc;
    }
    .eq-num {
      min-width: 32px;
      text-align: center;
    }
    .eq-op {
      color: #ef4444;
      font-size: 28px;
    }
    .eq-op.add-op {
      color: #f59e0b;
    }
    .eq-res {
      padding: 2px 10px;
      border-radius: 8px;
      background: #fef08a;
      color: #854d0e;
    }
    .controls {
      display: flex;
      justify-content: center;
      gap: 8px;
    }
    .step-pill {
      padding: 6px 14px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 700;
      background: #f1f5f9;
      color: #64748b;
      border: none;
      cursor: pointer;
      transition: all 0.2s ease;
    }
    .step-pill.active {
      background: #1e293b;
      color: #ffffff;
    }
  </style>
</head>
<body>

<div class="main">
  <div class="toggle-row">
    <button class="toggle-btn active sub" id="subBtn" onclick="setMode('sub')">
      <span>➖</span> Take Away
    </button>
    <button class="toggle-btn" id="addBtn" onclick="setMode('add')">
      <span>➕</span> Join Together
    </button>
  </div>

  <div class="stage-card">
    <div class="pond-area" id="pond"></div>

    <div class="equation-bar">
      <span class="eq-num" id="n1">8</span>
      <span class="eq-op" id="op">−</span>
      <span class="eq-num" id="n2">3</span>
      <span>=</span>
      <span class="eq-res" id="res">5</span>
    </div>

    <div class="controls">
      <button class="step-pill active" id="s1" onclick="setStep(1)">1. Start</button>
      <button class="step-pill" id="s2" onclick="setStep(2)">2. Action</button>
      <button class="step-pill" id="s3" onclick="setStep(3)">3. Left</button>
    </div>
  </div>
</div>

<script>
  let mode = 'sub'; // 'sub' or 'add'
  let step = 2;

  function render() {
    // Mode styling
    const subBtn = document.getElementById('subBtn');
    const addBtn = document.getElementById('addBtn');
    if (mode === 'sub') {
      subBtn.className = 'toggle-btn active sub';
      addBtn.className = 'toggle-btn';
      document.getElementById('op').textContent = '−';
      document.getElementById('op').className = 'eq-op';
      document.getElementById('n1').textContent = '8';
      document.getElementById('n2').textContent = (step >= 2) ? '3' : '?';
      document.getElementById('res').textContent = (step === 3) ? '5' : (step === 2 ? '5' : '?');
      document.getElementById('s3').textContent = '3. Left';
    } else {
      subBtn.className = 'toggle-btn';
      addBtn.className = 'toggle-btn active add';
      document.getElementById('op').textContent = '+';
      document.getElementById('op').className = 'eq-op add-op';
      document.getElementById('n1').textContent = '5';
      document.getElementById('n2').textContent = (step >= 2) ? '3' : '?';
      document.getElementById('res').textContent = (step >= 2) ? '8' : '?';
      document.getElementById('s3').textContent = '3. Total';
    }

    // Step buttons
    ['s1', 's2', 's3'].forEach((id, idx) => {
      document.getElementById(id).className = (idx + 1 === step) ? 'step-pill active' : 'step-pill';
    });

    // Pond items
    const pond = document.getElementById('pond');
    pond.innerHTML = '';

    if (mode === 'sub') {
      // 8 ducks total: 5 remain, 3 leave
      for (let i = 0; i < 8; i++) {
        const d = document.createElement('div');
        d.className = 'duck-slot';
        d.textContent = '🦆';
        if (i >= 5 && step >= 2) {
          d.classList.add('leaving');
        }
        pond.appendChild(d);
      }
    } else {
      // 5 original, 3 joining
      const total = (step === 1) ? 5 : 8;
      for (let i = 0; i < total; i++) {
        const d = document.createElement('div');
        d.className = 'duck-slot';
        d.textContent = '🦆';
        if (i >= 5) {
          d.classList.add('joining');
        }
        pond.appendChild(d);
      }
    }
  }

  function setMode(m) {
    mode = m;
    step = 2;
    render();
  }

  function setStep(s) {
    step = s;
    render();
  }

  render();
</script>

</body>
</html>

Here is a taking away story: *There are 8 ducks splashing in a pond. 3 ducks fly away. How many ducks are left in the pond?*

Because the ducks are leaving, the group gets smaller. We subtract to find what remains: $8 - 3 = 5$.

What if no items are added or taken away, but we want to see who has more?

When we compare two groups to find the **difference**, we also use **subtraction**.

<!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>Comparing Groups - Finding the Difference</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    }

    body {
      background-color: #faf5ff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 16px 12px;
      overflow-x: hidden;
    }

    .stepper-nav {
      display: flex;
      gap: 8px;
      margin-bottom: 12px;
      width: 100%;
      max-width: 440px;
    }

    .step-btn {
      flex: 1;
      padding: 8px 4px;
      border: 1px solid #e9d5ff;
      background: #ffffff;
      color: #6b7280;
      font-size: 13px;
      font-weight: 600;
      border-radius: 20px;
      cursor: pointer;
      text-align: center;
      transition: all 0.3s ease;
    }

    .step-btn.active {
      background: #8b5cf6;
      color: #ffffff;
      border-color: #8b5cf6;
      box-shadow: 0 2px 8px rgba(139, 92, 246, 0.3);
    }

    .stage {
      width: 100%;
      max-width: 440px;
      background: #ffffff;
      border: 1px solid #ede9fe;
      border-radius: 16px;
      padding: 18px 14px;
      display: flex;
      flex-direction: column;
      gap: 16px;
      position: relative;
    }

    .row {
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .name-badge {
      width: 68px;
      font-size: 13px;
      font-weight: 700;
      padding: 6px 8px;
      border-radius: 10px;
      text-align: center;
      flex-shrink: 0;
    }

    .mia-badge {
      background: #f3e8ff;
      color: #7e22ce;
    }

    .ben-badge {
      background: #fef3c7;
      color: #b45309;
    }

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

    .item-slot {
      aspect-ratio: 1;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 10px;
      font-size: 22px;
      position: relative;
      transition: all 0.3s ease;
      background: #fafafa;
    }

    .star {
      display: inline-block;
      line-height: 1;
      transition: transform 0.3s ease, opacity 0.3s ease;
      filter: drop-shadow(0 1px 2px rgba(0,0,0,0.1));
    }

    /* Step 2: Matched pairs styling */
    .matched .item-slot.paired {
      background: #f5f3ff;
      box-shadow: inset 0 0 0 1.5px #c4b5fd;
    }

    /* Step 3: Difference highlights */
    .difference-mode .item-slot.paired {
      opacity: 0.45;
    }

    .difference-mode .item-slot.extra {
      background: #fef08a;
      box-shadow: 0 0 0 2px #eab308;
      animation: pulse 1.6s infinite ease-in-out;
    }

    @keyframes pulse {
      0%, 100% { transform: scale(1); }
      50% { transform: scale(1.06); }
    }

    .connector-row {
      position: absolute;
      left: 92px;
      right: 14px;
      top: 50%;
      transform: translateY(-50%);
      display: grid;
      grid-template-columns: repeat(6, 1fr);
      gap: 6px;
      pointer-events: none;
      height: 16px;
    }

    .link-line {
      display: flex;
      justify-content: center;
      align-items: center;
      opacity: 0;
      transition: opacity 0.3s ease;
      font-size: 14px;
      font-weight: bold;
      color: #8b5cf6;
    }

    .matched .link-line.paired,
    .difference-mode .link-line.paired {
      opacity: 0.8;
    }

    .math-bar {
      margin-top: 10px;
      width: 100%;
      max-width: 440px;
      background: #ffffff;
      border: 1px solid #ede9fe;
      border-radius: 12px;
      padding: 10px 16px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      min-height: 48px;
    }

    .equation {
      font-size: 20px;
      font-weight: 800;
      color: #1e2945;
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .eq-num {
      padding: 2px 6px;
      border-radius: 6px;
    }

    .eq-mia { color: #7e22ce; background: #f3e8ff; }
    .eq-ben { color: #b45309; background: #fef3c7; }
    .eq-diff { color: #854d0e; background: #fef08a; border: 1.5px solid #eab308; }

    .status-tag {
      font-size: 12px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #8b5cf6;
    }

    @media (max-width: 380px) {
      .item-slot { font-size: 18px; }
      .name-badge { width: 56px; font-size: 11px; padding: 4px; }
      .equation { font-size: 17px; }
      .connector-row { left: 78px; }
    }
  </style>
</head>
<body>

  
  <div class="stepper-nav">
    <button class="step-btn active" onclick="setStep(0)">1. Line Up</button>
    <button class="step-btn" onclick="setStep(1)">2. Match</button>
    <button class="step-btn" onclick="setStep(2)">3. Difference</button>
  </div>

  
  <div class="stage" id="stage">
    
    
    <div class="connector-row">
      <div class="link-line paired">↕</div>
      <div class="link-line paired">↕</div>
      <div class="link-line paired">↕</div>
      <div class="link-line paired">↕</div>
      <div class="link-line"></div>
      <div class="link-line"></div>
    </div>

    
    <div class="row">
      <div class="name-badge mia-badge">Mia (6)</div>
      <div class="items-grid">
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot extra"><span class="star">⭐</span></div>
        <div class="item-slot extra"><span class="star">⭐</span></div>
      </div>
    </div>

    
    <div class="row">
      <div class="name-badge ben-badge">Ben (4)</div>
      <div class="items-grid">
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot paired"><span class="star">⭐</span></div>
        <div class="item-slot" style="background: transparent; border: 1px dashed #e2e8f0;"></div>
        <div class="item-slot" style="background: transparent; border: 1px dashed #e2e8f0;"></div>
      </div>
    </div>

  </div>

  
  <div class="math-bar">
    <span class="status-tag" id="statusLabel">Compare</span>
    <div class="equation" id="eqContainer">
      <span class="eq-num eq-mia">6</span>
      <span>−</span>
      <span class="eq-num eq-ben">4</span>
      <span>=</span>
      <span class="eq-num eq-diff">?</span>
    </div>
  </div>

  <script src="{{VENDOR_CDN}}/classace-diagram.js"></script>
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    const buttons = document.querySelectorAll('.step-btn');
    const statusLabel = document.getElementById('statusLabel');
    const eqContainer = document.getElementById('eqContainer');

    const stepsData = [
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        label: 'Compare',
        ans: '?'
      },
      {
        cls: 'matched',
        label: 'Match 4 Pairs',
        ans: '?'
      },
      {
        cls: 'difference-mode',
        label: 'Difference',
        ans: '2'
      }
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      });

      // Update stage class
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      // Update text & math
      statusLabel.textContent = stepsData[index].label;
      eqContainer.innerHTML = `
        <span class="eq-num eq-mia">6</span>
        <span>−</span>
        <span class="eq-num eq-ben">4</span>
        <span>=</span>
        <span class="eq-num eq-diff">${stepsData[index].ans}</span>
      `;
    }

    // Auto cycle through steps with calm pace
    setInterval(() => {
      setStep((currentStep + 1) % 3);
    }, 3800);
  </script>
</body>
</html>

Try this comparison: *Mia has 6 stars and Ben has 4 stars. How many more stars does Mia have than Ben?*

Even though you see the word *more*, we are not making a bigger group. We are finding the gap between 6 and 4, so $6 - 4 = 2$.

Watch out for word traps: do not just look for one word like *more*! Always ask yourself, *Did the total grow, or are we finding a smaller part?*

<!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: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
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    background: #ffffff;
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    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 12px;
    min-height: 100%;
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  .nav-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 12px;
    width: 100%;
    max-width: 440px;
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  .tab-btn {
    flex: 1;
    display: flex;
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    font-weight: 700;
    border-radius: 12px;
    border: 2px solid transparent;
    cursor: pointer;
    background: #f1f5f9;
    color: #64748b;
    transition: all 0.25s ease;
    user-select: none;
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  .tab-btn.active-add {
    background: #dcfce7;
    color: #15803d;
    border-color: #86efac;
    box-shadow: 0 2px 8px rgba(22, 163, 74, 0.15);
  }

  .tab-btn.active-sub {
    background: #fee2e2;
    color: #b91c1c;
    border-color: #fca5a5;
    box-shadow: 0 2px 8px rgba(220, 38, 38, 0.15);
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  .stage {
    position: relative;
    width: 100%;
    max-width: 440px;
    height: 250px;
    border-radius: 16px;
    overflow: hidden;
  }

  .view-panel {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    padding: 16px;
    border-radius: 16px;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease, transform 0.3s ease;
    transform: scale(0.98);
  }

  .view-panel.active {
    opacity: 1;
    pointer-events: auto;
    transform: scale(1);
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  .panel-add {
    background: #f0fdf4;
    border: 2px solid #bbf7d0;
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  .panel-sub {
    background: #fef2f2;
    border: 2px solid #fecaca;
  }

  .header-tag {
    font-size: 16px;
    font-weight: 800;
    display: flex;
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    gap: 6px;
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  .panel-add .header-tag { color: #166534; }
  .panel-sub .header-tag { color: #991b1b; }

  .vis-area {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 100%;
    flex: 1;
    gap: 12px;
  }

  .blocks-row {
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    align-items: center;
    justify-content: center;
    gap: 6px;
  }

  .block-group {
    display: flex;
    gap: 5px;
    padding: 6px;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.7);
  }

  .cube {
    width: 34px;
    height: 34px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-weight: 700;
    transition: all 0.4s ease;
  }

  .cube-green {
    background: #22c55e;
    color: #ffffff;
    box-shadow: 0 3px 0 #15803d;
  }

  .cube-coral {
    background: #ef4444;
    color: #ffffff;
    box-shadow: 0 3px 0 #b91c1c;
  }

  .cube-removed {
    opacity: 0.3;
    border: 2px dashed #dc2626;
    background: transparent;
    color: #dc2626;
    box-shadow: none;
    transform: translateY(-4px);
  }

  .symbol-icon {
    font-size: 22px;
    font-weight: 900;
    width: 28px;
    text-align: center;
  }
  .panel-add .symbol-icon { color: #16a34a; }
  .panel-sub .symbol-icon { color: #dc2626; }

  .action-arrow {
    font-size: 18px;
    line-height: 1;
    color: #64748b;
  }

  .equation-badge {
    font-size: 22px;
    font-weight: 900;
    letter-spacing: 1px;
    padding: 6px 20px;
    border-radius: 999px;
    background: #ffffff;
    box-shadow: 0 2px 6px rgba(0,0,0,0.06);
  }
  .panel-add .equation-badge { color: #15803d; border: 1.5px solid #86efac; }
  .panel-sub .equation-badge { color: #b91c1c; border: 1.5px solid #fca5a5; }
</style>
</head>
<body>

<div class="nav-tabs">
  <button id="tabAdd" class="tab-btn active-add" onclick="showMode('add')">
    <span>+</span> Total Grows
  </button>
  <button id="tabSub" class="tab-btn" onclick="showMode('sub')">
    <span>−</span> Smaller Part
  </button>
</div>

<div class="stage">
  
  <div id="viewAdd" class="view-panel panel-add active">
    <div class="header-tag">
      <span>✦</span> Total Grows
    </div>

    <div class="vis-area">
      <div class="blocks-row">
        <div class="block-group">
          <div class="cube cube-green">1</div>
          <div class="cube cube-green">2</div>
          <div class="cube cube-green">3</div>
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        <div class="symbol-icon">+</div>
        <div class="block-group">
          <div class="cube cube-green">4</div>
          <div class="cube cube-green">5</div>
        </div>
      </div>

      <div class="action-arrow">↓</div>

      <div class="block-group">
        <div class="cube cube-green">1</div>
        <div class="cube cube-green">2</div>
        <div class="cube cube-green">3</div>
        <div class="cube cube-green">4</div>
        <div class="cube cube-green">5</div>
      </div>
    </div>

    <div class="equation-badge">3 + 2 = 5</div>
  </div>

  
  <div id="viewSub" class="view-panel panel-sub">
    <div class="header-tag">
      <span>✦</span> Smaller Part
    </div>

    <div class="vis-area">
      <div class="block-group">
        <div class="cube cube-coral">1</div>
        <div class="cube cube-coral">2</div>
        <div class="cube cube-coral">3</div>
        <div class="cube cube-coral cube-removed">✕</div>
        <div class="cube cube-coral cube-removed">✕</div>
      </div>

      <div class="action-arrow">↓</div>

      <div class="block-group">
        <div class="cube cube-coral">1</div>
        <div class="cube cube-coral">2</div>
        <div class="cube cube-coral">3</div>
      </div>
    </div>

    <div class="equation-badge">5 − 2 = 3</div>
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</div>

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    document.getElementById('viewSub').classList.toggle('active', !isAdd);
  }
</script>

</body>
</html>

Next time you read a math story, act it out with your fingers or blocks first to see what the numbers are doing!

math

Choosing Between Addition and Subtraction. Analyze word problem scenarios to decide whether addition or subtraction is required.

Early Level & KS1: Addition and Subtraction Word Problems and Stories

Addition and Subtraction Intro: Word Problems within 10

Addition and Subtraction Word Problems with Pictures - Up to 10

At Early Level (P1 / ages 4–6), students master operation choice primarily through story dramatization, physical manipulation (CPA approach), and structured dialogue. Teachers should use 'First-Then-Now' story mats to make the passage of time and physical actions (joining vs. separating) explicit before introducing the abstract $+$, $-$, and $=$ symbols.

Choosing Between Addition and Subtraction

Joining Means Addition

Taking Away Means Subtraction