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A painter paints a roof. A mason tiles a floor. Each needs the area: how much flat surface a shape covers. Which lengths give it?

Your book's chapter is Area, Part II, Chapter 7. It measures flat shapes with straight sides.

What you will learn

• Counting squares — a partly covered square counts as the part it holds.
• Without counting — multiply the two sides.
• Cut and slide — a leaning shape becomes a rectangle.
• Half a parallelogram — two triangles make one.
• The height — square across (at a right angle), not the slanted side.
• A trapezium — four sides, at least one pair parallel. Average that pair.
• Awkward outlines — split an odd shape into triangles and rectangles.
• Square units — a square metre is bigger than it sounds.

Every idea has a lab. Tap or slide, and watch the area follow.