MATHS
A compound shape is made of rectangles joined together, and an 11+ question usually leaves some side lengths off the diagram. The child has to work them out before adding up the perimeter. In this lesson your child drags a highlighted side across the shape to see where the missing length comes from.
The method is simple: parallel sides on opposite edges add up to the same total. Each missing side is the full span minus the piece you already know. The lesson then shows how to walk round the shape and count every side once.
Question: An L-shape has a top of 8 cm, a left side of 6 cm, an inner horizontal step of 5 cm and a short right side of 2 cm. What is the perimeter?
Answer: The bottom is 8 − 5 = 3 cm, and the inner vertical side is 6 − 2 = 4 cm. Adding all six sides gives 8 + 2 + 5 + 4 + 3 + 6 = 28 cm.
This lesson suits children aged 8 to 11 who can find the perimeter of a rectangle but stop when a length is missing from the diagram.
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