Numbers: An idea that tells us how many things there are.

Counting: 🍎 → 1, 🍎🍎 → 2, 🍎🍎🍎 → 3

Comparison: 🍎🍎🍎🍎🍎(5) > 🍎🍎(2), 🍎🍎🍎🍎(4) = 🍎🍎🍎🍎(4)

Even numbers: Can be grouped into pairs with nothing left over (e.g., 4: 🍎🍎 | 🍎🍎)

Odd numbers: Have one left over when making pairs (e.g., 5: 🍎🍎 | 🍎🍎 | 🍎)