Area of compound shapes
PROCEDURALRecognise area as additive; find areas of rectilinear figures by decomposing into non-overlapping rectangles and summing their areas
Mastery Evidence
- Decompose an L-shape into two rectangles, find each area, and add them
- Find the area of a floor plan shaped like a T by splitting into rectangles
- Solve: A room is L-shaped (3m×5m plus 2m×4m) — what is the total area?
Assessment Prompt
“If [child] is given an L-shaped room on squared paper, can they split it into two rectangles, find the area of each part, and add them to get the total area?”
Prerequisites1
- Understanding angles (age 8+)hardAges 8—9
Show full prerequisite tree
- Understanding angles (age 8+) hard
Must find rectangle areas before decomposing rectilinear figures into rectangles
- Area by Tiling hard
Must see tiling→multiplication connection before computing area via side lengths
- Measuring length (age 7+) soft
Length measurement experience supports understanding area as a 2D measurement
- Measuring length (age 6+) hard
Using standard measurement tools extends measuring with non-standard units
- Measuring length and height (age 5+) hard
Measuring with iterated units extends Y1 beginning to measure length
- Comparing Lengths & Heights hard
Measuring length with units requires first being able to compare lengths directly
- Measurable Attributes of Objects hard
Comparing lengths/heights requires first identifying length as a measurable attribute
- Comparing Lengths & Heights hard
Ordering 3 objects by length and indirect comparison extends direct length comparison
- Measurable Attributes of Objects hard
Comparing lengths/heights requires first identifying length as a measurable attribute
- Capacity and volume hard
Using standard units for capacity extends from beginning to measure capacity
- Comparing Capacity hard
Measuring capacity with units requires first being able to compare capacities
- Measurable Attributes of Objects hard
Comparing capacity requires understanding capacity as a measurable attribute
- Measuring length and height (age 5+) hard
Using standard units for length extends from beginning to measure length
- Comparing Lengths & Heights hard
Measuring length with units requires first being able to compare lengths directly
- Measurable Attributes of Objects hard
Comparing lengths/heights requires first identifying length as a measurable attribute
- Measuring mass and weight (age 4+) hard
Measuring mass with units requires first being able to compare masses directly
- Measurable Attributes of Objects hard
Comparing mass/weight requires first identifying mass as a measurable attribute
Unlocks1
- Perimeter of Compound ShapessoftAges 9—10