Grade 4 › G4U09 Area & Angles

Grade 4 › G4U09 Area & Angles › L1
GRADE 4 · ALBERTAOUTCOME AB-G4-4M1

L1 · Area by Tiling: Units Without Gaps or Overlaps

Learning goal

“I can measure the area of a surface by tiling it with equal-sized units that cover it with no gaps and no overlaps - and I can count the units by rows.”

Area — the amount of surface inside a shape's border; how much space it covers.
Tiling — covering a surface with many copies of the same unit, placed edge to edge.
Gap / overlap — a gap is a bit of surface left uncovered; an overlap is where one unit sits on top of another. A good tiling has neither.
Square centimetre (cm²) — a square with sides 1 cm long; the standard unit for measuring area in this unit. About the size of a fingernail.
Worked example

We tile a book cover with sticky notes. Every note is the same size, they sit edge to edge, and the cover is completely hidden - no gaps, no overlaps. Step 1: Count the rows: there are 4 rows. Step 2: Count the notes in one row: 3 notes. Step 3: The cover is covered by 4 rows of 3 notes: 3 + 3 + 3 + 3 = 12, or 4 x 3 = 12. The area of the cover is 12 sticky notes. Say it plainly: area is a COUNT of units that cover a surface. The unit must be the same size every time, and the covering must be complete.

Check yourself — explain it

The sticky notes work as an area unit because...

Paired problem — example still visible

A placemat is tiled with square tiles: 3 rows of 5 tiles. Area? -> 15 tiles (3 x 5)

Faded completion — last step is yours

"A tray is tiled in 6 rows of 4 unit squares: 4 + 4 + 4 + 4 + 4 + 4 = ___ unit squares, so the area is ___ unit squares" -> 24; 24

Ready to practise?

10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.

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