Tile arrays: see why multiplication properties work
Before you start: Count equal rows and columns and add small groups.
Read an array as equal groups
An array with 3 rows and 6 tiles in each row contains 6 + 6 + 6 = 18 tiles, written 3 × 6. Counting the same 18 tiles one by one works, but multiplication records the equal-group structure. The row lengths must match for a rectangular array.
Turn the array: the commutative property
Rotate the rectangle so that its 6 columns become 6 rows of 3. No tile is added or removed, so 3 × 6 = 6 × 3. This illustrates ab = ba for whole-number arrays. The result applies to multiplication, not every operation: 6 − 3 = 3, while 3 − 6 = −3.
Split the array: the distributive property
Keep all 3 rows, but split each row into 4 blue and 2 gold tiles. There are 3 × 4 = 12 blue tiles and 3 × 2 = 6 gold tiles. Therefore 3 × (4 + 2) = 12 + 6 = 18. The same three rows occur in both smaller rectangles, which explains why the 3 multiplies both parts.
The expression 3 × 4 + 2 counts only 12 blue tiles and 2 gold tiles, a total of 14. It misses four gold tiles. The difference is visible on the board, so the correction follows from counting rather than memorising a slogan.
Use the picture for mental calculation and algebra
To find 7 × 14, split 14 into 10 + 4: 7 × 10 + 7 × 4 = 70 + 28 = 98. For a symbolic extension, (x + 2)(x + 3) splits a rectangle into four areas: x², 3x, 2x and 6. Their sum is x² + 5x + 6. Positive side lengths suit this physical picture; the algebraic identity has a wider domain.
Try it yourself
Split a 4-row, 7-column array into 5 columns and 2 columns. Write the two products and their sum.
Show answer and explanation
The smaller arrays contain 4 × 5 = 20 and 4 × 2 = 8 tiles. Thus 4 × (5 + 2) = 20 + 8 = 28. Both parts retain all four rows.
Use the activity to check your understanding
After a turn or split, explain what changed and what stayed the same. Use the visible tile counts to justify the equation.